Add badge for the XMPP chat room

README.md

 # converse.js
 
-[![Greenkeeper badge](https://badges.greenkeeper.io/jcbrand/converse.js.svg)](https://greenkeeper.io/)
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+[![inVerse](https://inverse.chat/badge.svg?room=discuss@conference.conversejs.org)](https://inverse.chat/#converse/room?jid=discuss@conference.conversejs.org)
 [![Travis](https://api.travis-ci.org/jcbrand/converse.js.png?branch=master)](https://travis-ci.org/jcbrand/converse.js)
 [![Bountysource bounties](https://img.shields.io/bountysource/team/converse.js/activity.svg?maxAge=2592000)](https://www.bountysource.com/teams/converse.js/issues?tracker_ids=194169)
 [![Translation status](https://hosted.weblate.org/widgets/conversejs/-/svg-badge.svg)](https://hosted.weblate.org/engage/conversejs/?utm_source=widget)