Merge pull request #7521 from doctrine/update-chat-link

Update chat link from Gitter to Slack.

docs/en/index.rst

@@ -13,9 +13,9 @@ If this documentation is not helping to answer questions you have about
 Doctrine ORM don't panic. You can get help from different sources:
 
 -  There is a :doc:`FAQ <reference/faq>` with answers to frequent questions.
--  The `Doctrine Mailing List <http://groups.google.com/group/doctrine-user>`_
--  Internet Relay Chat (IRC) in #doctrine on Freenode
--  Report a bug on `JIRA <http://www.doctrine-project.org/jira>`_.
+-  The `Doctrine Mailing List <https://groups.google.com/group/doctrine-user>`_
+-  Slack chat room `#orm <https://www.doctrine-project.org/slack>`_
+-  Report a bug on `GitHub <https://github.com/doctrine/doctrine2/issues>`_.
 -  On `Twitter <https://twitter.com/search/%23doctrine2>`_ with ``#doctrine2``
 -  On `StackOverflow <http://stackoverflow.com/questions/tagged/doctrine2>`_
 
@@ -72,9 +72,9 @@ Advanced Topics
 * :doc:`Transactions and Concurrency <reference/transactions-and-concurrency>`
 * :doc:`Filters <reference/filters>`
 * :doc:`NamingStrategy <reference/namingstrategy>`
-* :doc:`Improving Performance <reference/improving-performance>` 
-* :doc:`Caching <reference/caching>` 
-* :doc:`Partial Objects <reference/partial-objects>` 
+* :doc:`Improving Performance <reference/improving-performance>`
+* :doc:`Caching <reference/caching>`
+* :doc:`Partial Objects <reference/partial-objects>`
 * :doc:`Change Tracking Policies <reference/change-tracking-policies>`
 * :doc:`Best Practices <reference/best-practices>`
 * :doc:`Metadata Drivers <reference/metadata-drivers>`
@@ -103,7 +103,7 @@ Cookbook
 * **Patterns**:
   :doc:`Aggregate Fields <cookbook/aggregate-fields>` |
   :doc:`Decorator Pattern <cookbook/decorator-pattern>` |
-  :doc:`Strategy Pattern <cookbook/strategy-cookbook-introduction>` 
+  :doc:`Strategy Pattern <cookbook/strategy-cookbook-introduction>`
 
 * **DQL Extension Points**:
   :doc:`DQL Custom Walkers <cookbook/dql-custom-walkers>` |