Add #hubot channel badge

Author: geekgonecrazy

README.md

@@ -1,5 +1,6 @@
 ![Rocket.Chat logo](https://rocket.chat/images/logo/logo-dark.svg?v3)
 
+[![Rocket.Chat](https://demo.rocket.chat/api/v1/shield.svg?type=channel&name=Rocket.Chat&channel=hubot)](https://demo.rocket.chat/channel/hubot)
 [![Test Coverage](https://codeclimate.com/github/RocketChat/hubot-rocketchat/badges/coverage.svg)](https://codeclimate.com/github/RocketChat/hubot-rocketchat/coverage)
 [![Code Climate](https://codeclimate.com/github/RocketChat/hubot-rocketchat/badges/gpa.svg)](https://codeclimate.com/github/RocketChat/hubot-rocketchat)
 [![MIT License](http://img.shields.io/badge/license-MIT-blue.svg?style=flat)](https://github.com/RocketChat/Rocket.Chat/raw/master/LICENSE)