Some fixes and rewords

Author: javiereguiluz

routing/external_resources.rst

@@ -134,30 +134,40 @@ The path of each route being loaded from the new routing resource will now
 be prefixed with the string ``/site``.
 
 Prefixing the Names of Imported Routes
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-You have the possibility to prefix all routes names with the ``@Route`` annotation.
-Add a ``name`` property to the ``@Route`` annotation of the controller class and that will be considered the prefix of all route names
-
-.. code-block:: php
-      use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
-
-      /**
-       * @Route("/blog", name="blog_")
-       */
-      class BlogController extends Controller
-      {
-          /**
-           * @Route("/", defaults={"page": "1"}, name="index")
-           * @Route("/page/{page}", name="index_paginated")
-           */
-          public function indexAction($page, $_format) { ... }
-
-          /**
-           * @Route("/posts/{slug}", name="post")
-           */
-          public function showAction(Post $post) { ... }
-      }
-      
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 3.4
+    The feature to prefix route names was introduced in Symfony 3.4.
+
+You also have the possibility to prefix all route names defined in a controller
+class with the ``name`` attribute of the ``@Route`` annotation::
+
+    use Symfony\Component\Routing\Annotation\Route;
+
+    /**
+     * @Route(name="blog_")
+     */
+    class BlogController extends Controller
+    {
+        /**
+         * @Route("/blog", name="index")
+         */
+        public function indexAction()
+        {
+            // ...
+        }
+
+        /**
+         * @Route("/blog/posts/{slug}", name="post")
+         */
+        public function showAction(Post $post)
+        {
+            // ...
+        }
+    }
+
+In this example, the names of the routes will be ``blog_index`` and ``blog_post``.
+
 Adding a Host Requirement to Imported Routes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~