minor #18358 [Mailer] Update mailer.rst (Bloedewicht)

This PR was merged into the 6.3 branch.

Discussion
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[Mailer] Update mailer.rst

wrong composer packagename

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Commits
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6d13a0d Update mailer.rst

Author: javiereguiluz

mailer.rst

@@ -108,7 +108,7 @@ Service               Install with
 `Mailgun`_            ``composer require symfony/mailgun-mailer``
 `Mailjet`_            ``composer require symfony/mailjet-mailer``
 `MailPace`_           ``composer require symfony/mail-pace-mailer``
-`MailerSend`_         ``composer require symfony/mailersend-mailer``
+`MailerSend`_         ``composer require symfony/mailer-send-mailer``
 `Postmark`_           ``composer require symfony/postmark-mailer``
 `SendGrid`_           ``composer require symfony/sendgrid-mailer``
 `Sendinblue`_         ``composer require symfony/sendinblue-mailer``