community[patch]: docstrings (#16810)

- added missed docstrings
- formated docstrings to the consistent form

libs/community/langchain_community/utilities/vertexai.py

@@ -57,7 +57,7 @@ def init_vertexai(
     location: Optional[str] = None,
     credentials: Optional["Credentials"] = None,
 ) -> None:
-    """Init vertexai.
+    """Init Vertex AI.
 
     Args:
         project: The default GCP project to use when making Vertex API calls.