minor #17202 [Mailer] Update example to use Address format (jdelaune)

This PR was merged into the 5.4 branch.

Discussion
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[Mailer] Update example to use Address format

It seems strange to me that the example for the From headers uses the full Address format, whereas the sender envelope does not.

I believe it is possible to use it here, so thought I would expand on the example to show how you can set both the display name and email address when configuring the sender envelope globally.

Commits
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19d9617 Update example to use Address format

Author: javiereguiluz

mailer.rst

@@ -553,7 +553,7 @@ and headers.
         framework:
             mailer:
                 envelope:
-                    sender: '[email protected]'
+                    sender: 'Fabien <[email protected]>'
                     recipients: ['[email protected]', '[email protected]']
                 headers:
                     From: 'Fabien <[email protected]>'
@@ -575,7 +575,7 @@ and headers.
             <framework:config>
                 <framework:mailer>
                     <framework:envelope>
-                        <framework:sender>[email protected]</framework:sender>
+                        <framework:sender>Fabien &lt;[email protected]&gt;</framework:sender>
                         <framework:recipients>[email protected]</framework:recipients>
                         <framework:recipients>[email protected]</framework:recipients>
                     </framework:envelope>
@@ -595,7 +595,7 @@ and headers.
             $mailer = $framework->mailer();
             $mailer
                 ->envelope()
-                    ->sender('[email protected]')
+                    ->sender('Fabien <fabien@example.com>')
                     ->recipients(['[email protected]', '[email protected]'])
             ;