### 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:
7be5d113d8
Signed-off-by: Yikun Jiang <yikunkero@gmail.com>