[Mailer] Tweaked version notice for require_tls option

Co-authored-by: Maxime Doutreluingne <maxime.doutreluingne@gmail.com>

Author: ssddanbrown

mailer.rst

@@ -441,7 +441,7 @@ with the SMTP server.
 
 .. versionadded:: 7.3
 
-    The option to require TLS was introduced in Symfony 7.3.
+    The ``require_tls`` option was introduced in Symfony 7.3.
 
 Binding to IPv4 or IPv6
 ~~~~~~~~~~~~~~~~~~~~~~~