[Doc] fix offline inference and online serving describe (#285)

Signed-off-by: David Chen <530634352@qq.com>

docs/user_guide/examples/online_serving/qwen2_5_omni.md

@@ -1,4 +1,4 @@
-# Online serving Example of vLLM-Omni for Qwen2.5-Omni
+# Qwen2.5-Omni
 
 Source <https://github.com/vllm-project/vllm-omni/tree/main/examples/online_serving/qwen2_5_omni>.
 

docs/user_guide/examples/online_serving/qwen3_omni.md

@@ -1,4 +1,4 @@
-# Online serving Example of vLLM-Omni for Qwen3-omni
+# Qwen3-Omni
 
 Source <https://github.com/vllm-project/vllm-omni/tree/main/examples/online_serving/qwen3_omni>.