[Twig] Update the docs of the twig.debug option

Author: javiereguiluz

reference/configuration/twig.rst

@@ -155,6 +155,9 @@ debug
 If ``true``, the compiled templates include a ``__toString()`` method that can
 be used to display their nodes.
 
+This option also controls the behavior of :ref:`the Twig dump utilities <twig-dump-utilities>`.
+If this option is ``false``, the ``dump()`` function doesn't output any contents.
+
 .. _config-twig-default-path:
 
 default_path

templates.rst

@@ -818,6 +818,8 @@ and also to check the Twig features added when :ref:`installing packages <symfon
     # pass a template path to show the physical file which will be loaded
     $ php bin/console debug:twig @Twig/Exception/error.html.twig
 
+.. _twig-dump-utilities:
+
 The Dump Twig Utilities
 ~~~~~~~~~~~~~~~~~~~~~~~