Add DocumentManager used namespace

quick_tour/the_router.rst

@@ -151,6 +151,7 @@ Now you can add a new ``Route`` to the tree using Doctrine::
 
     use Doctrine\Common\Persistence\ObjectManager;
     use Doctrine\Common\DataFixtures\FixtureInterface;
+    use Doctrine\ODM\PHPCR\DocumentManager;
 
     use PHPCR\Util\NodeHelper;