minor #13945 Removed Mailer component docs (wouterj)

This PR was merged into the 4.4 branch.

Discussion
----------

Removed Mailer component docs

See symfony/symfony#37542

The component is quite easy to use in a standalone project. The example in the component's README will be enough I think (no need to confuse framework users by adding the examples in this doc).

Meanwhile, I'm not sure what to do with the Mime component. Should we move it into a subguide (`/mailer/mime.rst`)? It doesn't really make sense to have it as a main guide I think.

Commits
-------

225de94 Removed Mailer component docs

Author: xabbuh

_build/conf.py

@@ -127,7 +127,8 @@
     'rst': 'reStructuredText',
     'varnish2': 'Varnish 2',
     'varnish3': 'Varnish 3',
-    'varnish4': 'Varnish 4'
+    'varnish4': 'Varnish 4',
+    'env': '.env'
 }
 
 # don't enable Sphinx Domains

_build/redirection_map

@@ -505,3 +505,4 @@
 /components/class_loader https://github.com/symfony/class-loader
 /frontend/encore/versus-assetic /frontend
 /components/http_client /http_client
+/components/mailer /mailer

components/mailer.rst

@@ -218,7 +218,7 @@ Your own Sender
 Imagine that you already have an ``ImportantAction`` message going through the
 message bus and being handled by a handler. Now, you also want to send this
 message as an email (using the :doc:`Mime </components/mime>` and
-:doc:`Mailer </components/mailer>` components).
+:doc:`Mailer </mailer>` components).
 
 Using the :class:`Symfony\\Component\\Messenger\\Transport\\Sender\\SenderInterface`,
 you can create your own message sender::

components/messenger.rst

@@ -61,11 +61,7 @@ methods to compose the entire email message::
     ;
 
 This only purpose of this component is to create the email messages. Use the
-:doc:`Mailer component </components/mailer>` to actually send them. In Symfony
-applications, it's easier to use the :doc:`Mailer integration </mailer>`.
-
-Most of the details about how to create Email objects, including Twig integration,
-can be found in the :doc:`Mailer documentation </mailer>`.
+:doc:`Mailer component </mailer>` to actually send them.
 
 Twig Integration
 ----------------