Bug 1641182 - doc: Add a link to the quick reference doc

Differential Revision: https://phabricator.services.mozilla.com/D77054

docs/setup/contributing_code.rst

@@ -8,6 +8,8 @@ in the `#introduction <https://chat.mozilla.org/#/room/#introduction:mozilla.org
 We make changes to Firefox by writing patches, testing them and pushing them into "the tree", the
 term we use for all the code in Mozilla-Central. Let's get started.
 
+Please see the :ref:`Firefox Contributors’ Quick Reference` for simple check list.
+
 Finding something to work on
 ----------------------------