Add missing Mailersend step (laravel#9592)

* Add missing Mailersend step

* Update mail.md

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: Svenlaa

mail.md

@@ -188,6 +188,14 @@ MAIL_FROM_NAME="App Name"
 MAILERSEND_API_KEY=your-api-key
 ```
 
+Finally, add MailerSend to the `mailers` array in your application's `config/mail.php` configuration file:
+
+```php
+'mailersend' => [
+    'transport' => 'mailersend',
+],
+```
+
 To learn more about MailerSend, including how to use hosted templates, consult the [MailerSend driver documentation](https://github.com/mailersend/mailersend-laravel-driver#usage).
 
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