[Doc] Add release note for v0.9.1rc3 (#2488)

### What this PR does / why we need it?

Add release note for `v0.9.1rc3`.

- vLLM version: v0.10.0
- vLLM main:
vllm-project/vllm@5341565

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Signed-off-by: shen-shanshan <[email protected]>

Author: shen-shanshan