Add Thredded Forums

Not sure if it fits this list, as the setup is a bit more involved.

Thredded has a Rails app generator and a set of Ansible playbooks for provisioning and deployment.

README.md

@@ -446,6 +446,7 @@ _[IPBX](https://en.wikipedia.org/wiki/IP_PBX) telephony software_
 - [Talkyard](https://www.talkyard.io/) - Create a community, where your users can suggest ideas and get questions answered. And have friendly open-ended discussions and chat (Slack/StackOverflow/Discourse/Reddit/Disqus hybrid). ([Demo](https://www.talkyard.io/forum/latest), [Source Code](https://github.com/debiki/talkyard)) `AGPL-3.0` `Scala`
 - [Telescope](http://www.telescopeapp.org/) - Open-source social news app built with Meteor. ([Demo](http://demo.telescopeapp.org/), [Source Code](https://github.com/TelescopeJS/Telescope)) `MIT` `Nodejs`
 - [Tokumei](https://tokumei.co/) - Anonymous microblogging platform. ([Demo](https://demo.tokumei.co/), [Source Code](https://git.tokumei.co/tokumei/tokumei)) `ISC` `rc`
+- [Thredded](https://thredded.org) - Forums, feature-rich and simple. ([Demo](https://thredded.org/), [Source Code](https://github.com/thredded/thredded), [Ansible](https://github.com/thredded/thredded-ansible)) `MIT` `Ruby`
 - [twister](http://twister.net.co/) - Fully decentralized P2P microblogging platform leveraging the free software implementations of Bitcoin and BitTorrent protocols. ([Source Code](https://github.com/miguelfreitas/twister-core)) `MIT` `C++`
 - [Vanilla Forums](https://vanillaforums.org/) - Simple and flexible forum software. ([Source Code](https://github.com/vanilla/vanilla)) `GPL-2.0` `PHP`