docs: add docs for BC fusion (bnb-chain#255)

* docs: add docs for BC fusion preparation

docs/bcfusion/overview.md

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+# Overview
+
+BNB Beacon Chain is a blockchain developed by the BNB Chain community that implements a vision of a decentralized
+exchange (DEX) for digital assets. Besides this, Beacon Chain and BSC is a dual-chain structure: Beacon Chain helps to
+enhance the security of BSC as a staking and governance layer. With the rise of various other forms of Dex, order-book
+based decentralized exchange was decommissioned
+in [BEP151](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP151.md). With the quick evolution of BSC, the Beacon
+Chain has become a burden. The cross-chain bridge that connects the two chains slows down the development iteration and
+always exposes BNB to a certain level of security vulnerabilities. It's time to take a step further and migrate the
+functionality of Beacon Chain to BSC, **allowing Beacon Chain to retire**.
+
+![img](../assets/bcfusion/phases.png)
+
+There will be several pahses to retrie Beacon Chain:
+
+- **First Sunset Fork** - Some types of Beacon chain transactions will be disabled, for example, TimeLockMsg,
+  TimeRelockMsg,
+  FreezeMsg, IssueMsg, MintMsg, IssueMiniMsg, HTLTMsg, DepositHTLTMsg, MsgCreateValidatorOpen,
+  MsgCreateSideChainValidator, MsgCreateSideChainValidatorWithVoteAddr, MsgEditSideChainValidatorWithVoteAddr,
+  MsgSideChainDelegate, MsgSideChainReDelegate. (Estimated time on mainnet: 2024 Feb)
+- **BSC Feynman Hardfork** - Native validators and staking, native goverenance will be enabled on BNB Smart Chain.
+  The BSC validators/delegators can start migrations after the Feynman upgrade. (Estimated time on mainnet: 2024 Apr)
+- **Second Sunset Fork** - More Beacon chain transactions will be disabled, for example,MsgSideChainSubmitProposal. All
+  TimeLock and AtomicSwap will automatically be refunded to the user's
+  wallet. All the BSC delegation will be undelegated automatically. (Estimated time on mainnet: 2024 Jun)
+- **Final Sunset Fork** - Cross-chain communication between the Beacon Chain and BSC will be completely stopped. (
+  Estimated time on mainnet: 2024 Jun)
+- **Post BC Fusion** - Beacon Chain will be dumped and and a merkle tree will be generated for recover the assets, which
+  are binded to BSC however not transffered to BSC yet.
+
+All stakholders (e.g., token holders/owners, validators, project owners) should pay attention BNB Chain blog for
+releated annonuncements and take actions proactively.
+
+For more information about BNB Chain fusion, please refer
+to [BEP-333](https://github.com/bnb-chain/BEPs/pull/333?ref=bnbchain.ghost.io).
+
+For the roadmap and milestons of BNB Chain fusion, please refer
+to [the blog](https://www.bnbchain.org/en/blog/bnb-chain-fusion-roadmap).
+

docs/bcfusion/owners/bind.md

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+# Token Bind
+
+Token binding was introduced to faciliate that one token can circulate in both BC and BSC with confirmed total supply. 
+- If a token is binded, then it can be transferred bewteen BC and BSC for different use cases.
+After [the final sunset
+hardfork](https://github.com/bnb-chain/bEPs/pull/333), the cross chain between BC and BSC will be shutdown. 
+However, users still can use token recover tool to recover the binded assets on BSC (but it is much more complex compared to crosschain transfer).
+- If a token is not binded, after the final sunset hardfork, the assets cannot be recovered anymore. 
+Token owners or issuers should take actions to bind their valueable tokens.
+
+***NOTE: The BC Fusion program is scheduled for implementation in April 2024. Please ensure careful planning for the
+asset migration and keep the fund safe.***
+
+Please check the tutorial [**Confirm if the Assets Support Cross-chain Transfers**](../users/assets.md) to verify if the
+token allows cross-chain
+transfers. If the answer is positive, congratulations! You don't need
+to do anything. Otherwise, it is highly recommended to follow the
+[Token Bind Tool](https://github.com/bnb-chain/token-bind-tool) to
+deploy a BEP20 token on BSC and enable cross-chain functionality.
+
+Due to the time limitation, the Token Issuer should take actions as soon as possbile. It is
+recommended that the Token Issuer use multiple channels to promptly
+notify asset holders to migrate as soon as possible.
+
+***Note: BEP2/BEP8 assets that do not support cross-chain functionality
+will be permanently lost after BC Fusion. Users will be unable to
+recover these assets forever.***

docs/bcfusion/users/assets.md

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+import Wallet1 from '../../assets/bcfusion/user-asset-management3.png';
+import Wallet2 from '../../assets/bcfusion/user-asset-management4.png';
+import Tw1 from '../../assets/bcfusion/tw1.PNG';
+import Tw2 from '../../assets/bcfusion/tw2.PNG';
+
+# Asset Management
+
+The BNB Chain community recently introduced [BEP333: BNB Chain
+Fusion](https://github.com/bnb-chain/BEPs/pull/333). This
+BEP aims to retire the BNB Beacon Chain from the BNB Chain ecosystem.
+The goal is to enhance the development efficiency, security, and asset
+utilization efficiency of BSC. It also aims to reduce the maintenance
+costs of legacy services. This tutorial aims to help digital asset
+issuers and holders on the BNB Beacon Chain transfer the value of their
+assets,
+including [BEP2](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP2.md)/[BEP8](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP8.md)
+tokens, before and after BC Fusion. By following this guide, users can
+avoid any potential losses of their valuable digital assets.
+
+***NOTE: The BC Fusion program is scheduled for implementation in April 2024. Please ensure careful planning for the
+asset migration and keep the fund safe.***
+
+## Before BC Fusion
+
+Most valuable BEP2/BEP8 tokens such as BNB, BTC, and BUSD can freely
+move between the Beacon Chain and BSC networks. Users are strongly
+advised to transfer their assets to the BSC network to ensure a seamless
+and lossless transition, maintaining a 1:1 ratio. Of course, there are
+alternative channels available for asset transfers, such as utilizing
+centralized exchanges or decentralized cross-chain exchanges like
+Binance.com and [Thorswap](https://thorswap.finance/).
+However, these options are beyond the scope of this tutorial.
+
+**Step1: Confirm if the Assets Support Cross-chain Transfers**
+
+Open the Beacon Chain blockchain explorer, go to the [BEP2
+Asset](https://explorer.bnbchain.org/assets/bep2) page or
+[BEP8 Asset](https://explorer.bnbchain.org/assets/bep8)
+page, and search for the token name to query it. Using BTC as an
+example, it is linked to a BSC Contract address, allowing for
+cross-chain transfers.
+
+![img](../../assets/bcfusion/user-asset-management1.png)
+
+In contrast to GTEX-71B, which lacks a BSC Contract address and thus
+does not support cross-chain transfers.
+
+![img](../../assets/bcfusion/user-asset-management2.png)
+
+If a user needs to transfer assets that don't support cross-chain
+transfers, it's strongly recommended to contact the token owner/issuer
+as soon as possible. **Ask the token issuer to refer to [the token bind tutorial](../owners/bind.md) for issuing BEP20
+tokens on BSC and
+enabling cross-chain transfers. If the token issuer does not enable
+cross-chain transfer for the token before the sunset of BNB Beacon
+Chain, the funds will be lost forever and can not be recovered.**
+
+**Step2: Simply Transfer the Assets to the BSC Network**
+
+[BNB Chain Wallet](https://chromewebstore.google.com/detail/bnb-chain-wallet/fhbohimaelbohpjbbldcngcnapndodjp)
+and [Trust Wallet](https://trustwallet.com/) mobile are suggested for this case. Taking BNB Chain Wallet as an example,
+once users import the accounts that have the tokens, they need to switch the
+network to "BNB Beacon Chain Network":
+
+<img src={Wallet1} width="400"/>
+
+
+Then, select the asset to transfer, enter the BSC account and the token
+amount.
+
+<img src={Wallet2} width="400"/>
+
+The BSC wallet will receive the token after approximately one minute.
+
+For Trust Wallet mobile multi-chain wallet users, they can transfer their assets in the following way.
+
+<img src={Tw1} width="400"/>
+
+Firstly, you need to open the `Swap` tab, choose From network as `BNB Beacon Chain` and To network as `BNB Smart Chain`,
+then find the asset you want to transfer and input the transfer amount.
+After you click the `Continue` button, it will redirect you to the approval page as below.
+
+<img src={Tw2} width="400"/>
+
+Finally, the related asset will be transferred to BSC after you confirm the transaction.
+
+## After BC Fusion
+
+Following the retirement of Beacon Chain, it is believed that some users
+have not yet transferred their assets to the BSC network. BNB Chain is
+still providing relief measures for these users: [BEP299-Token
+Migration after BC
+Fusion](https://github.com/bnb-chain/BEPs/pull/299).
+
+Although this solution has its limitations, it is important to note the
+following key points:
+
+1. It is only applicable to assets that have enabled cross-chain features. **The BEP2/BEP8 assets will be permanently
+   lost** **if not the case.**
+
+2. Users are still responsible for securely storing their private keys on the Beacon Chain and using them for signing as
+   proof.
+
+3. The process of recovering assets will take up to 7 days to complete.
+
+4. This solution is operated through the command line and does not provide any UI.
+
+Considering these limitations, it is highly recommended that users
+complete the token transfer before BC fusion as much as possible.
+
+The detailed guide for this solution will be published after the BC
+Fusion.
+Stay tuned for the update.
+
+

docs/bcfusion/users/delegations.md

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+This page will guide users to manage their delegations.
+Please be patient for updates.

docs/bcfusion/users/swaps.md

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+# Atomic Swap Management
+
+HTLC based atomic swaps are introduced in
+[BEP3](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP3.md),
+to facilitate payment and asset exchanges between different blockchains.
+For BC fusion, in [the first sunset
+hardfork](https://github.com/bnb-chain/bEPs/pull/333), the
+creation and deposit of atomic swaps will be disabled, project owners
+(e.g., cross-chain exchanges, bridges) and users should be aware of this
+and take proactive steps.
+
+## Query Atomic Swaps
+
+The [atomic swap api](https://docs.bnbchain.org/docs/beaconchain/develop/api-reference/dex-api/paths#apiv1atomic-swaps)
+is provided to query existing atomic swaps. Usually, user can provide a
+from address to query the related atomic swaps, for example:
+
+[https://dex.bnbchain.org/api/v1/atomic-swaps?fromAddress=bnb1xz3xqf4p2ygrw9lhp5g5df4ep4nd20vsywnmpr](https://dex.bnbchain.org/api/v1/atomic-swaps?fromAddress=bnb1xz3xqf4p2ygrw9lhp5g5df4ep4nd20vsywnmpr)
+
+![img](../../assets/bcfusion/user-atomic-swap1.png)
+
+The response will contain a lot of useful information, such as id of the
+swap, the asset of the swap, and other information.
+
+## Handle Atomic Swaps
+
+### Before BC Fusion
+
+A user can proactively refund his/her atomic swaps by sending **HTLC Refund** transactions to Beacon Chain. The command
+to send such
+transaction is looks like this:
+
+```shell
+./bnbcli token refund --swap-id <swapID> --from <from-key> --chain-id Binance-Chain-Tigris --trust-node --node http://dataseed1.bnbchain.org:80
+```
+
+For more information about the command, please refer to
+the [Refund HTLC section](https://docs.bnbchain.org/docs/beaconchain/atomic-swap#refund-htlt).
+
+If no proactive refunds are submitted, in [the second sunset hardfork](https://github.com/bnb-chain/bEPs/pull/333), all
+existing atomic swaps will be automatically refunded to the creators'
+accounts on Beacon Chain. The refund will proceed in many Beacon Chain
+blocks, depending on how many atomic swaps still exist on the
+blockchain. After refund, users should be able to find the assets in
+their accounts. Then users can handle the assets as other BEP2/BEP8
+tokens. For how to cross transfer them to BNB Smart Chain, please
+refer to [this tutorial](./assets.md).
+
+### After BC Fusion
+
+If the refunded assets are not transferred to BSC
+before [the final sunset fork](https://github.com/bnb-chain/bEPs/pull/333),
+users need to use the token-recover tool to get their binded BEP2/BEP8
+assets. For more information, please refer to [this
+tutorial](https://docs.google.com/document/d/1rMWwYGt-s6FXcRiUrBSN8dtOU96HDz0T3GaZyzbo7VQ/edit?pli=1#heading=h.df0svx3bznak).
+
+## For Atomic Swap Project Owers
+
+Because in [the first sunset hardfork](https://github.com/bnb-chain/bEPs/pull/333), the
+creation and deposit of atomic swaps will be disabled, so project owners
+need to disable related functions in their projects IN ADVANCE and
+notify their uses to take proactive actions to refund their tokens.
+
+## Other Useful References
+
+- [Refund Atomic Swap](https://docs.bnbchain.org/docs/beaconchain/atomic-swap#refund-htlt)
+
+- [Query Atomic Swap](https://docs.bnbchain.org/docs/beaconchain/develop/api-reference/dex-api/paths#apiv1atomic-swaps)

docs/bcfusion/users/timelocks.md

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+# TimeLock Management
+
+A timelock is a feature that allows users to lock their assets for a certain period of time, which is introduced
+in (https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP9.md).
+For BC fusion, in [the second sunset
+hardfork](https://github.com/bnb-chain/bEPs/pull/333), all timelocks will be refunded to users' accounts.
+Users should proactively actionsj to transfer these assets to BSC after receiving the refunds.
+
+## Query TimeLocks
+
+The [time lock api](https://docs.bnbchain.org/docs/beaconchain/develop/api-reference/dex-api/paths#apiv1timelocksaddress)
+is provided to query existing timelocks. Usually, user can provide a
+from address to query the related timelocks, for example:
+
+[https://dex.bnbchain.org/api/v1/timelocks/bnb1rmet5j5pwc3xvhd82rwdjkvewzgmreh6we72sf](https://dex.bnbchain.org/api/v1/timelocks/bnb1rmet5j5pwc3xvhd82rwdjkvewzgmreh6we72sf)
+
+![img](../../assets/bcfusion/user-timelock1.png)
+
+The response will contain a lot of useful information, such as id of the
+timelock, the asset of the timelock, and the unlock time.
+
+## Handle TimeLocks
+
+Once the timelock is created, the owners cannot access their assets until the unlock time has passed.
+During [the second sunset hardfork](https://github.com/bnb-chain/bEPs/pull/333), all
+existing timelocks will be automatically refunded to the creators'
+accounts on Beacon Chain. The refund will proceed in many Beacon Chain
+blocks, depending on how many timelocks still exist on the
+blockchain. After refund, users should be able to find the assets in
+their accounts. Then users can handle the assets as other BEP2/BEP8
+tokens. For how to cross transfer them to BNB Smart Chain, please
+refer to [this tutorial](./assets.md).
+

docs/bcfusion/validators/creation.md

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+This page will guide validators to create new native BSC validators.
+Please be patient for updates.

docs/bcfusion/validators/migrations.md

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+This page will guide validators to migrate their BSC validators.
+Please be patient for updates.

sidebars.js

@@ -299,8 +299,43 @@ const sidebars = {
             label: 'opBNB',
             href:'https://docs.bnbchain.org/opbnb-docs/',
           },
-
-    ],
+
+          {
+              type: 'category',
+              label: '🌅BNB Beacon Chain Sunset',
+              collapsible: true,
+              collapsed: true,
+              items: [
+                  {type: 'doc', label: 'Overview', id:'bcfusion/overview'},
+                  {
+                      type: 'category',
+                      label:'For Users',
+                      items:[
+                          {type:'doc', id:'bcfusion/users/assets', label:'Manange Your Assets'},
+                          {type:'doc', id:'bcfusion/users/swaps', label:'Manage Your Atomic Swaps'},
+                          {type:'doc', id:'bcfusion/users/timelocks', label:'Manage Your TimeLocks'},
+                          {type:'doc', id:'bcfusion/users/delegations', label:'Manage Your Delegations'},
+                      ]
+                  },
+                  {
+                      type: 'category',
+                      label:'For Token Issuers',
+                      items:[
+                          {type:'doc', id:'bcfusion/owners/bind', label:'Bind Your Tokens'},
+                      ]
+                  },
+                  {
+                      type: 'category',
+                      label:'For Validators',
+                      items:[
+                          {type:'doc', id:'bcfusion/validators/migrations', label:'Migrate Your Validators'},
+                          {type:'doc', id:'bcfusion/validators/creation', label:'Create New Validators'},
+                      ]
+                  },
+              ],
+          },
+
+      ],
     },
     {
       type: 'category',