minor #18838 Modify method on route logout in security.rst (rschillinger)

This PR was submitted for the 6.3 branch but it was merged into the 5.4 branch instead.

Discussion
----------

Modify method on route logout in security.rst

There is an error regarding the method of the logout route in the controller.

Commits
-------

a156c31 Modify method on route logout in security.rst

Author: javiereguiluz

security.rst

@@ -1705,7 +1705,7 @@ Next, you need to create a route for this URL (but not a controller):
 
         class SecurityController extends AbstractController
         {
-            #[Route('/logout', name: 'app_logout', methods: ['POST'])]
+            #[Route('/logout', name: 'app_logout', methods: ['GET'])]
             public function logout()
             {
                 // controller can be blank: it will never be called!