[Bugfix][Qwen3-Omni] Fix synchronous Thinker pipeline parallelism (#7345)

Signed-off-by: Deep Shah <deep@socratic.co>

docs/user_guide/examples/online_serving/qwen3_omni.md

@@ -22,6 +22,10 @@ both stages on vLLM's Triton unquantized MoE path and avoids the unstable FlashI
 some GPUs.
 Asynchronous chunk streaming is **enabled by default** within the bundled configuration.
 
+For Thinker pipeline parallelism, configure `pipeline_parallel_size` and `devices`
+on the Thinker stage and set `async_scheduling: false`. Keep Talker and Code2Wav
+at `pipeline_parallel_size: 1`. Audio chunk streaming can remain enabled.
+
 To explicitly utilize a custom deployment YAML, specify the configuration path:
 ```bash
 vllm serve Qwen/Qwen3-Omni-30B-A3B-Instruct --omni --port 8091 \