minor #16741 [Security] Fix tag attribute in event XML example (jontjs)

This PR was submitted for the 6.0 branch but it was merged into the 5.4 branch instead.

Discussion
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[Security] Fix tag attribute in event XML example

This corrects the spelling of the "dispatcher" attribute (from "dispacher").

Commits
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979bf2a Fix tag attribute in event XML example

Author: javiereguiluz

security.rst

@@ -2561,7 +2561,7 @@ for these events.
 
                     <service id="App\EventListener\CustomLogoutSubscriber">
                         <tag name="kernel.event_subscriber"
-                             dispacher="security.event_dispatcher.main"
+                             dispatcher="security.event_dispatcher.main"
                          />
                     </service>
                 </services>