community[patch]: docstrings (#16810)

- added missed docstrings
- formated docstrings to the consistent form

libs/community/langchain_community/chat_models/gpt_router.py

@@ -53,6 +53,8 @@ class GPTRouterException(Exception):
 
 
 class GPTRouterModel(BaseModel):
+    """GPTRouter model."""
+
     name: str
     provider_name: str