minor #14471 Syntax fix (Nyholm)

This PR was merged into the 5.x branch.

Discussion
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Syntax fix

This will make sure the build is green again

Commits
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f79b268 Syntax fix

Author: javiereguiluz

notifier/chatters.rst

@@ -101,7 +101,7 @@ some interactive options called `Block elements`_::
 .. _`Block elements`: https://api.slack.com/reference/block-kit/block-elements
 
 Adding Interactions to a Discord Message
---------------------------------------
+----------------------------------------
 
 With a Discord message, you can use the
 :class:`Symfony\\Component\\Notifier\\Bridge\\Discord\\DiscordOptions` to add