Updated README for the Mailer component

Author: wouterj

README.md

@@ -3,9 +3,66 @@ Mailer Component
 
 The Mailer component helps sending emails.
 
+Getting Started
+---------------
+
+```
+$ composer require symfony/mailer
+```
+
+```php
+use Symfony\Component\Mailer\Transport;
+use Symfony\Component\Mailer\Mailer;
+
+$transport = Transport::fromDsn('sendgrid://KEY@default');
+$mailer = new Mailer($transport);
+
+$email = (new Email())
+    ->from('[email protected]')
+    ->to('[email protected]')
+    //->cc('[email protected]')
+    //->bcc('[email protected]')
+    //->replyTo('[email protected]')
+    //->priority(Email::PRIORITY_HIGH)
+    ->subject('Time for Symfony Mailer!')
+    ->text('Sending emails is fun again!')
+    ->html('<p>See Twig integration for better HTML integration!</p>');
+
+$mailer->send($email);
+```
+
+To enable the Twig integration of the Mailer, require `symfony/twig-bridge` and
+set up the `BodyRenderer`:
+
+```php
+use Symfony\Bridge\Twig\Mime\BodyRenderer;
+use Symfony\Component\EventDispatcher\EventDispatcher;
+use Symfony\Component\Mailer\EventListener\MessageListener;
+use Twig\Environment as TwigEnvironment;
+
+$twig = new TwigEnvironment(...);
+$messageListener = new MessageListener(new BodyRenderer($twig));
+
+$eventDispatcher = new EventDispatcher();
+$eventDispatcher->addSubscriber($messageListener);
+
+$mailer = new Mailer($transport, null, $eventDispatcher);
+
+$email = (new TemplatedEmail())
+    // ...
+    ->htmlTemplate('emails/signup.html.twig')
+    ->context([
+        'expiration_date' => new \DateTime('+7 days'),
+        'username' => 'foo',
+    ])
+;
+$mailer->mail($email);
+```
+
 Resources
 ---------
 
+  * [Documentation](https://symfony.com/doc/current/mailer.html)
   * [Contributing](https://symfony.com/doc/current/contributing/index.html)
   * [Report issues](https://github.com/symfony/symfony/issues) and
     [send Pull Requests](https://github.com/symfony/symfony/pulls)