Updated documentation

firebase_admin/messaging.py

@@ -284,6 +284,7 @@ def __init__(self, headers=None, data=None, notification=None):
 
 
 class WebpushNotificationAction(object):
+    """An action available to the users when the notification is presented."""
 
     def __init__(self, action, title, icon=None):
         self.action = action