[Docs] Add docstring to User.active_sessions

calsocial/models.py

@@ -229,6 +229,9 @@ class User(db.Model, UserMixin):
 
     @property
     def active_sessions(self):
+        """The list of active sessions of this user
+        """
+
         return cache.get(self.session_list_key) or []
 
     @active_sessions.setter