Update routing.rst

Author: ThomasLandauer

routing.rst

@@ -2566,8 +2566,10 @@ Generating URLs
 ---------------
 
 Routing systems are bidirectional:
+
 1. they associate URLs with controllers (as explained in the previous sections);
 2. they generate URLs for a given route.
+
 Generating URLs from routes allows you to not write the ``<a href="...">``
 values manually in your HTML templates. Also, if the URL of some route changes,
 you only have to update the route configuration and all links will be updated.