minor #17275 [Twig] Document the new methods of AppVariable (javiereguiluz)

This PR was squashed before being merged into the 6.2 branch.

Discussion
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[Twig] Document the new methods of AppVariable

Fixes #17265.

Commits
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f8a6efa [Twig] Document the new methods of AppVariable

Author: javiereguiluz

templates.rst

@@ -377,6 +377,17 @@ gives you access to these variables:
 ``app.token``
     A :class:`Symfony\\Component\\Security\\Core\\Authentication\\Token\\TokenInterface`
     object representing the security token.
+``app.current_route``
+    The name of the route associated to the current request or ``null`` if no
+    request is available (equivalent to ``app.request.attributes.get('_route')``)
+``app.current_route_parameters``
+    An array with the parameters passed to the route of the current request or an
+    empty array if no request is available (equivalent to ``app.request.attributes.get('_route_params')``)
+
+.. versionadded:: 6.2
+
+    The ``app.current_route`` and ``app.current_route_parameters`` variables
+    were introduced in Symfony 6.2.
 
 In addition to the global ``app`` variable injected by Symfony, you can also
 :doc:`inject variables automatically to all Twig templates </templating/global_variables>`.