Simplify CONTRIBUTING. Don't have to follow Proton repo

Author: Jove Zhong

CONTRIBUTING.md

@@ -4,16 +4,6 @@
 
 # Contributing
 
-Proton is an open project, and you can contribute to it in many ways. You can help with ideas, code, or documentation. We appreciate any efforts that help us to make the project better. If you are looking for issues to work on, try looking at [the issue list](https://github.com/timeplus-io/proton/issues).
+Proton is an open project, and you can contribute to it in many ways. This is the Rust client for Proton. You can help with ideas, code, or documentation. We appreciate any efforts that help us to make the project better.
 
 Thank you!
-
-## Legal Info
-
-When you open your first pull-request to Proton repo, a bot will invite you to accept Proton Individual CLA (Contributor License Agreement). It is a simple few click process. For subsequent pull-requests the bot will check if you have already signed it and won't bother you again.
-
-## Technical Info
-
-Please follow the Proton code convention (TODO) and [Clickhouse coding style](https://clickhouse.com/docs/en/development/style) and write unit test / integration testing (TODO). See [build from source](BUILD.md) for how to compile Proton in different platforms. Besides this guide, you can find [Overview of Proton Architecture](https://docs.timeplus.com/proton-architecture) 
-
-If you want to contribute to documentation, please submit PR to https://github.com/timeplus-io/docs.