Update contribution guidelines to mention mailing list

CONTRIBUTING.rst

@@ -4,14 +4,22 @@ Contributing to Converse.js
 
 Thanks for contributing to Converse.js_.
 
+Support questions
+=================
+
+Please ask support and setup questions on the mailing list: conversejs@librelist.com
+The issue tracker is only for bugs (i.e. issues) and feature requests.
+
+Contributing Code
+=================
 Please follow the usual github workflow. Create your own local fork of this repository,
 make your changes and then submit a pull request.
 
 Before submitting a pull request
-================================
+--------------------------------
 
 Add tests for your bugfix or feature
-------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Add a test for any bug fixed or feature added. We use Jasmine
 for testing. 
@@ -23,7 +31,7 @@ If you are unsure how to write tests, please `contact me`_ and I'll be happy to
 help.
 
 Check that the tests pass
--------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Check that the Jasmine tests complete sucessfully. Open tests.html in your
 browser, and the tests will run automatically.
@@ -32,7 +40,7 @@ On the command line you can run ``grunt test`` (if you have before run ``npm
 install``).
 
 Check your code for errors or bad habits by running JSHint
-----------------------------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you haven't yet done so, run ``npm install`` to install all development
 dependencies.