Documented the Mime component

Author: javiereguiluz

components/mailer.rst

@@ -0,0 +1,25 @@
+.. index::
+   single: Mailer
+   single: Components; Mailer
+
+The Mailer Component
+====================
+
+    The Mailer component helps sending emails.
+
+Installation
+------------
+
+.. code-block:: terminal
+
+    $ composer require symfony/mailer
+
+Alternatively, you can clone the `<https://github.com/symfony/mailer>`_ repository.
+
+.. include:: /components/require_autoload.rst.inc
+
+Usage
+-----
+
+We're currently working on the documentation of this component that was just
+added to Symfony. We'll publish it in a few days.