docs: address API guide review feedback

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>

docs/serving/streaming_video_output_api.md

@@ -19,7 +19,7 @@ vllm serve BestWishYsh/Helios-Distilled --omni \
 Install the client dependency and run the provided client:
 
 ```bash
-pip install websockets
+pip install av websockets
 
 python examples/online_serving/streaming_video_generation/streaming_video_client.py \
   --host 127.0.0.1 \

examples/online_serving/minicpmo/README.md

@@ -47,7 +47,7 @@ scenario below for live barge-in validation on the target GPU.
 Default:
 
 ```bash
-vllm-omni serve openbmb/MiniCPM-o-4_5 \
+vllm serve openbmb/MiniCPM-o-4_5 \
     --omni \
     --deploy-config vllm_omni/deploy/minicpmo_4_5.yaml \
     --trust-remote-code \

examples/online_serving/streaming_video_generation/README.md

@@ -37,7 +37,7 @@ During generation the client normally sends only `session.start` and then receiv
 ## Install Client Dependency
 
 ```bash
-pip install websockets
+pip install av websockets
 # For the Gradio demo:
 pip install 'vllm-omni[demo]' websockets
 ```

examples/online_serving/streaming_video_generation/streaming_video_client.py

@@ -8,7 +8,7 @@ the received bytes to disk when the session finishes or is interrupted.
 Image/reference input is intentionally not supported in this example yet.
 
 Requirements:
-    pip install websockets
+    pip install av websockets
 """
 
 import argparse