added demo to discourse

README.md

@@ -368,7 +368,7 @@ _[IPBX](https://en.wikipedia.org/wiki/IP_PBX) telephony software_
   * [BuddyPress](https://buddypress.org/about/) - A powerful plugin that takes your WordPress.org powered site beyond the blog with social-network features like user profiles, activity streams, user groups, and more. ([Source Code](https://buddypress.svn.wordpress.org/trunk/)) `GPLv2` `PHP`
   * [cartulary](https://github.com/daveajones/cartulary) - RSS reader, readability tool, article archiver, microblogger, social graph manager and reading list manager. `CDDL` `PHP`
   * [diaspora*](https://diasporafoundation.org/) - Distributed social networking server. ([Demo](https://podupti.me/go.php), [Source Code](https://github.com/diaspora/diaspora)) `AGPLv3` `Ruby`
-  * [Discourse](http://www.discourse.org/) - Advanced forum / community solution based on Ruby and JS. ([Source Code](https://github.com/discourse/discourse)) `GPLv2` `Ruby`
+  * [Discourse](http://www.discourse.org/) - Advanced forum / community solution based on Ruby and JS. ([Demo](https://try.discourse.org/), [Source Code](https://github.com/discourse/discourse)) `GPLv2` `Ruby`
   * [dyu/comments](https://github.com/dyu/comments/) - A real-time, markdown-enabled comment engine powered by leveldb. ([Demo](https://dyu.github.io/comments/real-time/)) `Apache` `Java`
   * [Elgg](https://elgg.org/) - A powerful open source social networking engine. ([Source Code](https://github.com/Elgg/Elgg)) `GPLv2` `PHP`
   * [Flarum](http://flarum.org) - Delightfully simple forums. Flarum is the next-generation forum software that makes online discussion fun again. ([Source Code](https://github.com/flarum/flarum)) `MIT` `PHP`