### What this PR does / why we need it?
Add release note for v0.9.1rc2
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
CI passed
- vLLM version: v0.10.0
- vLLM main:
c494f96fbc
Signed-off-by: Yikun Jiang <yikunkero@gmail.com>