minor #11119 Add missing bracket on a php code example (GregOriol)

This PR was merged into the 4.2 branch.

Discussion
----------

Add missing bracket on a php code example

This fixes a typo that seems to have appeared in the docs v4.2.

Commits
-------

adf8111 Add missing bracket on a php code example

Author: javiereguiluz

routing.rst

@@ -566,7 +566,7 @@ placeholder:
         use App\Controller\BlogController;
 
         return function (RoutingConfigurator $routes) {
-            $routes->add('blog_list', '/blog/{page<\d+>?1')
+            $routes->add('blog_list', '/blog/{page<\d+>?1}')
                 ->controller([BlogController::class, 'list'])
             ;
         };