[Benchmark] Add local OmniInteract realtime benchmark (#6522)

Signed-off-by: natureofnature <wzliu@connect.hku.hk>

docs/cli/README.md

@@ -39,4 +39,5 @@ vllm bench serve --omni \
     --num-prompts  5
 ```
 
-See [vllm bench serve](./bench/serve.md) for the full reference of all available arguments.
+See [vllm bench serve](./bench/serve.md) for serving benchmark arguments and
+dataset-specific examples, including OmniInteract native-duplex sessions.