correct kwargs documentation in docstrings (#559)

Author: skarzi

firebase_admin/_auth_client.py

@@ -288,7 +288,7 @@ def create_user(self, **kwargs): # pylint: disable=differing-param-doc
         """Creates a new user account with the specified properties.
 
         Args:
-            kwargs: A series of keyword arguments (optional).
+            **kwargs: A series of keyword arguments (optional).
 
         Keyword Args:
             uid: User ID to assign to the newly created user (optional).
@@ -316,7 +316,7 @@ def update_user(self, uid, **kwargs): # pylint: disable=differing-param-doc
 
         Args:
             uid: A user ID string.
-            kwargs: A series of keyword arguments (optional).
+            **kwargs: A series of keyword arguments (optional).
 
         Keyword Args:
             display_name: The user's display name (optional). Can be removed by explicitly passing

firebase_admin/_http_client.py

@@ -104,7 +104,7 @@ class call this method to send HTTP requests out. Refer to
         Args:
           method: HTTP method name as a string (e.g. get, post).
           url: URL of the remote endpoint.
-          kwargs: An additional set of keyword arguments to be passed into the requests API
+          **kwargs: An additional set of keyword arguments to be passed into the requests API
               (e.g. json, params, timeout).
 
         Returns:

firebase_admin/_messaging_utils.py

@@ -341,7 +341,7 @@ class APNSPayload:
 
     Args:
         aps: A ``messaging.Aps`` instance to be included in the payload.
-        kwargs: Arbitrary keyword arguments to be included as custom fields in the payload
+        **kwargs: Arbitrary keyword arguments to be included as custom fields in the payload
             (optional).
     """
 

firebase_admin/auth.py

@@ -416,7 +416,7 @@ def create_user(**kwargs): # pylint: disable=differing-param-doc
     """Creates a new user account with the specified properties.
 
     Args:
-        kwargs: A series of keyword arguments (optional).
+        **kwargs: A series of keyword arguments (optional).
 
     Keyword Args:
         uid: User ID to assign to the newly created user (optional).
@@ -447,7 +447,7 @@ def update_user(uid, **kwargs): # pylint: disable=differing-param-doc
 
     Args:
         uid: A user ID string.
-        kwargs: A series of keyword arguments (optional).
+        **kwargs: A series of keyword arguments (optional).
 
     Keyword Args:
         display_name: The user's display name (optional). Can be removed by explicitly passing

firebase_admin/db.py

@@ -907,7 +907,7 @@ def request(self, method, url, **kwargs):
         Args:
           method: HTTP method name as a string (e.g. get, post).
           url: URL path of the remote endpoint. This will be appended to the server's base URL.
-          kwargs: An additional set of keyword arguments to be passed into requests API
+          **kwargs: An additional set of keyword arguments to be passed into requests API
               (e.g. json, params).
 
         Returns: