minor #20065 Fix a PHP config example (javiereguiluz)

This PR was merged into the 6.4 branch.

Discussion
----------

Fix a PHP config example

After merging #19597 I realized that it looks a bit different from the other PHP config examples, so I think this change is needed to make it work.

Commits
-------

17102f9 Fix a PHP config example

Author: OskarStark

reference/configuration/debug.rst

@@ -95,7 +95,7 @@ Typically, you would set this to ``php://stderr``:
     .. code-block:: php
 
         // config/packages/debug.php
-        use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+        namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
         return static function (ContainerConfigurator $container): void {
             $container->extension('debug', [