Remvoe obsolete docs

doc/filters/escape.rst

@@ -93,22 +93,6 @@ to learn more about this topic.
 Custom Escapers
 ---------------
 
-.. versionadded:: 3.10
-
-    The ``EscaperRuntime`` class has been added in 3.10. On previous versions,
-    you can define custom escapers by calling the ``setEscaper()`` method on
-    the escaper extension instance. The first argument is the escaper strategy
-    (to be used in the ``escape`` call) and the second one must be a valid PHP
-    callable::
-
-        use Twig\Extension\EscaperExtension;
-
-        $twig = new \Twig\Environment($loader);
-        $twig->getExtension(EscaperExtension::class)->setEscaper('csv', 'csv_escaper');
-
-    When called by Twig, the callable receives the Twig environment instance,
-    the string to escape, and the charset.
-
 You can define custom escapers by calling the ``setEscaper()`` method on the
 escaper runtime instance. It accepts two arguments: the strategy name and a PHP
 callable that accepts a string to escape and the charset::