Update introduction.rst

taavit · weaverryan · commit 5f696f567def · 2014-02-16T13:15:52.000-06:00
Found that use Symfony\Component\HttpKernel\EventListener\RouterListener; is missing
 in full working example.
diff --git a/components/http_kernel/introduction.rst b/components/http_kernel/introduction.rst
@@ -601,6 +601,7 @@ a built-in ControllerResolver that can be used to create a working example::
     use Symfony\Component\HttpKernel\HttpKernel;
     use Symfony\Component\EventDispatcher\EventDispatcher;
     use Symfony\Component\HttpKernel\Controller\ControllerResolver;
+    use Symfony\Component\HttpKernel\EventListener\RouterListener;
     use Symfony\Component\Routing\RouteCollection;
     use Symfony\Component\Routing\Route;
     use Symfony\Component\Routing\Matcher\UrlMatcher;
