[Docs] Add qwen image missing doc in user guide (#111)

Signed-off-by: samithuang <285365963@qq.com>

mkdocs.yml

@@ -87,6 +87,7 @@ plugins:
       show_full_namespace: false  # Show only module name, not full path
       exclude:
         - "re:vllm_omni\\._.*"  # Internal modules
+        - "vllm_omni.diffusion.models.qwen_image"  # avoid importing vllm in mkdocs building
   - mkdocstrings:
       handlers:
         python: