Update conversation_state.py (#590)

Added ref documentation.

Author: Michael Miele

libraries/botbuilder-core/botbuilder/core/conversation_state.py

@@ -7,16 +7,41 @@
 
 
 class ConversationState(BotState):
-    """Conversation State
-    Reads and writes conversation state for your bot to storage.
+    """Conversation state
+    Defines a state management object for conversation state.
+    Extends `BootState` base class.
+
+    .. remarks::
+        Conversation state is available in any turn in a specific conversation, regardless of user, such as in a group conversation.
     """
 
     no_key_error_message = "ConversationState: channelId and/or conversation missing from context.activity."
 
     def __init__(self, storage: Storage):
+        """ Creates a :class:ConversationState instance
+        Creates a new instance of the :class:ConversationState class.
+        :param storage: The storage containing the conversation state.
+        :type storage: Storage
+        """
         super(ConversationState, self).__init__(storage, "ConversationState")
 
     def get_storage_key(self, turn_context: TurnContext) -> object:
+        """ Get storage key
+        Gets the key to use when reading and writing state to and from storage.
+
+        :param turn_context: The context object for this turn.
+        :type turn_context: TurnContext 
+
+        :raise: `TypeError` if the `ITurnContext.Activity` for the current turn is missing 
+        :any::Schema.Activity.ChannelId or :any::Schema.Activity.Conversation information, or 
+        the conversation's :any::Schema.ConversationAccount.Id is missing.
+
+        :return: The storage key.
+        :rtype: str
+
+        .. remarks::
+            Conversation state includes the channel ID and conversation ID as part of its storage key.
+        """
         channel_id = turn_context.activity.channel_id or self.__raise_type_error(
             "invalid activity-missing channel_id"
         )
@@ -31,4 +56,7 @@ def get_storage_key(self, turn_context: TurnContext) -> object:
         return storage_key
 
     def __raise_type_error(self, err: str = "NoneType found while expecting value"):
+        """ Raise type error
+        :raises: :class:TypeError This function raises exception.
+        """
         raise TypeError(err)