Update gitter channel name
The old channel goes back to our old repository name, and all new Gitter
channels are under out GitHub/Gitter community namespace `readthedocs`.
There are a few channels there, but this is the most general channel.
@@ -16,7 +16,7 @@ Get in touch
.. _StackOverFlow: https://stackoverflow.com/questions/tagged/read-the-docs
.. _on GitHub: https://github.com/readthedocs/readthedocs.org
-.. _Gitter: https://gitter.im/rtfd/readthedocs.org
+.. _Gitter: https://gitter.im/readthedocs/community
Contributing to development
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