refactor(abigen): inline docs

[DaniPopes]

Motivation

Solution

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog
• Breaking changes

[mattsse]

lgtm

[gakonst]

error[E0599]: no function or associated item named `default` found for struct `seaport::BadContractSignature` in the current scope
   --> ethers-contract/tests/it/abigen.rs:649:73
    |
640 |     abigen!(Seaport, "./tests/solidity-contracts/seaport.json");
    |     ----------------------------------------------------------- function or associated item `default` not found for this struct
...
649 |     let err = SeaportErrors::BadContractSignature(BadContractSignature::default());
    |                                                                         ^^^^^^^ function or associated item not found in `seaport::BadContractSignature`
    |
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following traits define an item `default`, perhaps you need to implement one of them:
            candidate #1: `std::default::Default`
            candidate #2: `tinyvec::array::Array`

Seems to have broken something here? @DaniPopes

[mattsse]

looks like all infura keys are completely exhausted -.-

having #2075 would def help