minor #19821 [Security] Update login_link.rst (carlcasbolt)

This PR was submitted for the 7.0 branch but it was squashed and merged into the 6.4 branch instead.

Discussion
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[Security] Update login_link.rst

Missing use statements in CustomLoginLinkNotification example

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Commits
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cbf0283 [Security] Update login_link.rst

Author: javiereguiluz

security/login_link.rst

@@ -279,6 +279,8 @@ This will send an email like this to the user:
         // src/Notifier/CustomLoginLinkNotification
         namespace App\Notifier;
 
+        use Symfony\Component\Notifier\Message\EmailMessage;
+        use Symfony\Component\Notifier\Recipient\EmailRecipientInterface;
         use Symfony\Component\Security\Http\LoginLink\LoginLinkNotification;
 
         class CustomLoginLinkNotification extends LoginLinkNotification