Merge pull request #49 from heyrhett/master

update readme with warning about message_echoes

README.md

@@ -171,7 +171,7 @@ Create an Application on [developers.facebook.com] and go to the Messenger
 tab. Select the Page you want to install your bot on.
 
 Create a new webhook, enter the domain your bot is connected to and a verify
-token of your choosing.
+token of your choosing. NOTE: If you subscribe to message_echoes, the "Bot.on :message" block will try to process these.  This could potentially put your app in a bad feedback loop.
 
 ![Application settings](https://scontent-amt2-1.xx.fbcdn.net/hphotos-xfp1/t39.2178-6/12057143_211110782612505_894181129_n.png)