Docs: update CONTRIBUTING

CONTRIBUTING.md

@@ -12,7 +12,7 @@ We look forward to working with you to make this project better together!
 ## Becoming a contributor
 
 The first step is registering as a tRPC-Cpp contributor.
-Before sending your first change to the tRPC-Cpp project you must have [signed and submitted a CLA (Contributor License Agreement)](to-do).
+Before sending your first change to the tRPC-Cpp project you must have [signed and submitted a CLA (Contributor License Agreement)](https://github.com/trpc-group/cla-database/blob/main/README.md).
 
 ## Before contributing code
 
@@ -47,7 +47,7 @@ When opening an issue, make sure to answer these five questions:
 4. What did you expect to see?
 5. What did you see instead?
 
-For change proposals, see Proposing Changes To [tRPC-Proposals](to-do).
+For change proposals, see Proposing Changes To [tRPC-Proposals](https://github.com/trpc-group/trpc/blob/main/proposal/README.md).
 
 ## Contributing code
 

CONTRIBUTING.zh_CN.md

@@ -12,7 +12,7 @@
 ## 成为贡献者
 
 第一步是注册为 tRPC-Cpp 贡献者。
-向 tRPC-Cpp 项目发送您的第一个变更之前，您必须签署并提交[贡献者许可协议](to-do)。
+向 tRPC-Cpp 项目发送您的第一个变更之前，您必须签署并提交[贡献者许可协议](https://github.com/trpc-group/cla-database/blob/main/README.md)。
 
 ## 在贡献代码之前
 
@@ -47,7 +47,7 @@ issue 会被分类以管理工作流程。
 4. 您期望看到什么？
 5. 您实际看到的是什么？
 
-关于变更提案，请参阅向 [tRPC-Proposals](to-do) 提议变更。
+关于变更提案，请参阅向 [tRPC-Proposals](https://github.com/trpc-group/trpc/blob/main/proposal/README.zh_CN.md) 提议变更。
 
 ## 贡献代码