Update recipe_sortable_listing.rst

Resources/doc/cookbook/recipe_sortable_listing.rst

@@ -273,6 +273,7 @@ Resources
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 Adding a new action is explained in the Sonata documentation (http://sonata-project.org/bundles/admin/master/doc/reference/routing.html#create-a-route)
+
 Controller code has been inspired from http://www.symfony.it/articoli/690/sonata-e-sortable/