Merge branch '5.1'

* 5.1:
  Added some links
  Remove links to not existing channel pages

Author: javiereguiluz

notifier.rst

@@ -31,17 +31,19 @@ by using transports.
 
 The notifier component supports the following channels:
 
-* `SMS <SMS Channel>`_ sends notifications to phones via SMS messages
-* `Chat <Chat Channel>`_ sends notifications to chat services like Slack
-  and Telegram;
-* `Email <Email Channel>`_ integrates the :doc:`Symfony Mailer </mailer>`;
-* Browser uses :ref:`flash messages <flash-messages>`.
+* :ref:`SMS channel <notifier-sms-channel>` sends notifications to phones via
+  SMS messages;
+* :ref:`Chat channel <notifier-chat-channel>` sends notifications to chat
+  services like Slack and Telegram;
+* :ref:`Email channel <notifier-email-channel>` integrates the :doc:`Symfony Mailer </mailer>`;
+* Browser channel uses :ref:`flash messages <flash-messages>`.
 
 .. tip::
 
     Use :doc:`secrets </configuration/secrets>` to securily store your
     API's tokens.
 
+.. _notifier-sms-channel:
 .. _notifier-texter-dsn:
 
 SMS Channel
@@ -116,6 +118,7 @@ configure the ``texter_transports``:
             ],
         ]);
 
+.. _notifier-chat-channel:
 .. _notifier-chatter-dsn:
 
 Chat Channel
@@ -189,6 +192,8 @@ Chatters are configured using the ``chatter_transports`` setting:
             ],
         ]);
 
+.. _notifier-email-channel:
+
 Email Channel
 ~~~~~~~~~~~~~