[Routing] Update ignoreAttributes description

The documentation does not mention one can ignore all attributes or specify which of them to ignore. This is pretty clear to someone calling `\Symfony\Bundle\FrameworkBundle\Controller\RedirectController::redirectAction`, but not to someone using YAML.

Author: guhemama

routing.rst

@@ -1616,8 +1616,10 @@ Use the ``RedirectController`` to redirect to other routes and URLs:
                 # * for temporary redirects, it uses the 307 status code instead of 302
                 # * for permanent redirects, it uses the 308 status code instead of 301
                 keepRequestMethod: true
-                # add this to remove the original route attributes when redirecting
+                # add this to remove all original route attributes when redirecting
                 ignoreAttributes: true
+                # or specify which attributes to ignore
+                # ignoreAttributes: [ offset, limit ]
 
         legacy_doc:
             path: /legacy/doc