Update dev documentation for removal of jabber

Author: marc1706

development/development/upgrade/400.rst

@@ -40,6 +40,12 @@ The ban system has been greatly refactored for phpBB 4.0. As part of this, the f
 - Added support for IPv6 banning
 - Removed "exclude" functionality which resulted in ambiguous settings
 
+Removal of Jabber/XMPP
+----------------------
+The Jabber/XMPP functionality has been removed from phpBB 4.0. This includes the Jabber/XMPP settings in the ACP and the Jabber/XMPP notification system.
+Users with Jabber/XMPP accounts will no longer receive notifications via Jabber/XMPP and have instead been migrated to email notifications.
+The Jabber/XMPP functionality was removed due to the lack of support for the XMPP protocol in modern browsers and the fact that it was not widely used by phpBB users.
+
 Class and function changes
 ==========================
 The following table lists class and function changes that might affect custom PHP or Extension code.
@@ -391,6 +397,12 @@ Also have a look at the `phpBB API documentation <https://area51.phpbb.com/docs/
      - ``4.0.0-a1``
      - Use phpbb_build_radio() instead.
 
+   * - ``messenger``
+     - ``includes/functions_messenger.php``
+     - Refactored to new messenger system, removed jabber support
+     - ``4.0.0-a1``
+     - Added new refactored messenger system. See the API docs for `\\phpbb\\messenger <https://area51.phpbb.com/docs/code/master/phpbb/messenger.html>`_ namespace.
+
 **Explanation of columns:**
 
 * **Class or function:**  The name of the class or function that was added, changed, deprecated, or removed in this version.

development/extensions/tutorial_notifications.rst

@@ -651,14 +651,10 @@ you will have to indicate that in the path, e.g.: ``@vendor_extension/subdirecto
        return '@vendor_extension/sample';
    }
 
-There is also a third notification method, Jabber, which uses the :class:`email/short` directory for its template files.
-This notification method is closely tied to the email method, so it is important to also supply that template file,
-even though the content might be identical to the email template.
-
-.. warning::
+.. note::
 
-   Make sure to have both :class:`language/en/email/sample.txt` and :class:`language/en/email/short/sample.txt`
-   in your extension's language directory to prevent errors.
+    The previously existing Jabber notification method has been removed in phpBB 4.0. A separate :class:`email/short` directory
+    for this notification method is no longer used and therefore you no longer need to create a separate template file for it.
 
 get_email_template_variables
 ----------------------------