message: update readme to point to normal private convo functions
diff: @@ -220,6 +220,10 @@ For example, a bot may use these methods when handling a `bot_room_join` event
  in order to send a message to the _user who invited the bot_ (the actor) instead of
  the bot itself (the sender).
  +NOTE: Core functions like [bot.startPrivateConversation()](readme.md#botstartprivateconversation) and
  +[bot.createPrivateConversation()](readme.me#botcreateprivateconversation) work as expected,
  +and will create a direct message thread with the sender of the incoming_message.
  +
  ### bot.startPrivateConversationWithPersonId()
  | Parameter | Description
  |--- |---
  