minor #21121 fix: minor in file webhook.rst (santysisi)

This PR was merged into the 6.4 branch.

Discussion
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fix: minor in file `webhook.rst`

This PR includes a minor documentation fix for the Webhook component:

* Added a missing closing parenthesis in the example URL (https://example.com/webhook/mailer_mailgun).

Commits
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80a809c fix: minor in file `webhook.rst`

Author: xabbuh

webhook.rst

@@ -100,7 +100,7 @@ webhook consumer code.
 The webhook routing name is part of the URL you need to configure at the
 third-party mailer provider. The URL is the concatenation of your domain name
 and the routing name you chose in the configuration (like
-``https://example.com/webhook/mailer_mailgun``.
+``https://example.com/webhook/mailer_mailgun``).
 
 For Mailgun, you will get a secret for the webhook. Store this secret as
 MAILER_MAILGUN_SECRET (in the :doc:`secrets management system