Add link to the Slack support channel

Author: Grégoire Paris

contributing/code/bugs.rst

@@ -14,8 +14,9 @@ Before submitting a bug:
 * Double-check the official :doc:`documentation </index>` to see if you're not misusing the
   framework;
 
-* Ask for assistance on `Stack Overflow`_ or on the #symfony `IRC channel`_
-  if you're not sure if your issue is really a bug.
+* Ask for assistance on `Stack Overflow`_ on the #symfony `IRC channel`_, or on
+  the #support channel of `the Symfony Slack` if you're not sure if your issue
+  is really a bug.
 
 If your problem definitely looks like a bug, report it using the official bug
 `tracker`_ and follow some basic rules:
@@ -42,5 +43,6 @@ If your problem definitely looks like a bug, report it using the official bug
 
 .. _`Stack Overflow`: http://stackoverflow.com/questions/tagged/symfony2
 .. _IRC channel: https://symfony.com/irc
+.. _the Symfony Slack: https://symfony.com/slack-invite
 .. _tracker: https://github.com/symfony/symfony/issues
 .. _Symfony Standard Edition: https://github.com/symfony/symfony-standard/