minor #13774 Fixed typo in classname (flowl)

This PR was submitted for the master branch but it was merged into the 5.1 branch instead.

Discussion
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Fixed typo in classname

Cutom -> Custom

Commits
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aba6d8b Fixed typo in classname

Author: javiereguiluz

security.rst

@@ -1038,8 +1038,8 @@ event class:
             // config/services.php
             namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
-            use App\EventListener\CutomLogoutListener;
-            use App\EventListener\CutomLogoutSubscriber;
+            use App\EventListener\CustomLogoutListener;
+            use App\EventListener\CustomLogoutSubscriber;
             use Symfony\Component\Security\Http\Event\LogoutEvent;
 
             return function(ContainerConfigurator $configurator) {