minor #15015 [Security] fix file path in comment following namespace (pierreboissinot)

This PR was submitted for the 5.2 branch but it was merged into the 4.4 branch instead.

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[Security] fix file path in comment following namespace

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8ddf8ec fix file path in comment following namespace

Author: javiereguiluz

security/impersonating_user.rst

@@ -259,7 +259,7 @@ be called):
 Then, create a voter class that responds to this role and includes whatever custom
 logic you want::
 
-    // src/Service/Voter/SwitchToCustomerVoter.php
+    // src/Security/Voter/SwitchToCustomerVoter.php
     namespace App\Security\Voter;
 
     use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;