Add feature branch policy

[Yikun]

What this PR does / why we need it?

This patch add the feature branch policy.

After this patch: maintainers are allowed to create a feature branch. Feature branches are used for collaboration and must include an RFC link, merge plan and mentor info.

Does this PR introduce any user-facing change?

No

How was this patch tested?

CI passed

• vLLM version: v0.10.0
• vLLM main: vllm-project/vllm@7be5d11

[gemini-code-assist]

Code Review

This pull request introduces a feature branch policy and updates the documentation accordingly. The changes are a good step towards formalizing the development process. However, I've found a few inconsistencies and errors in the documentation that need to be addressed to ensure clarity and correctness. Specifically, the status of feature branches is inconsistent between files, information has been added to the wrong section in the Chinese README, and there's a grammatical error in the policy definition itself. Please see the detailed comments for suggestions.

[Yikun]

cc @wangxiyuan @ganyi1996ppo @jianzs @ApsarasX @MengqingCao @zzzzwwjj @jgong5

Considering that this is a content involving versioning policy, it is best to get reviews from most maintainers and active contributors. My main concern is maintenance cost and branches diverge too far, therefore, I added mentor and merge plan.

[wangxiyuan]

I think this line should be added once a new branch is really comming?

[Yikun]

This is just an index, I think it will not be changed in future.

[ApsarasX]

Maybe we can refer to WebAssembly/proposals to tier our feature branches.

[github-actions]

👋 Hi! Thank you for contributing to the vLLM Ascend project. The following points will speed up your PR merge:‌‌

• A PR should do only one thing, smaller PRs enable faster reviews.
• Every PR should include unit tests and end-to-end tests ‌to ensure it works and is not broken by other future PRs.
• Write the commit message by fulfilling the PR description to help reviewer and future developers understand.

If CI fails, you can run linting and testing checks locally according Contributing and Testing.

[MengqingCao]

lgtm

[Yikun]

Maybe we can refer to WebAssembly/proposals to tier our feature branches.

Thanks for info, this PR is only for feature branch, but not for proposal workflow. But I think your link about proposals is also very useful to help us manage proprosals.

[wangxiyuan]

please fix the lint error, then let's merge this

[Yikun]

Thanks all @ganyi1996ppo @MengqingCao @ApsarasX Let's first merge this to see feature branch works as our expected! If it's unexpected, please feel free to tell me, we can revert this policy.