minor #5121 As per twigphp/Twig#472, automatic escaping is not yet available (Ocramius)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #5121).

Discussion
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As per twigphp/Twig#472, automatic escaping is not yet available

While it would be a cool feature, it is also impossible to apply automatic escaping in most cases.
Advertising this as a out-of-the-box feature is problematic, as it probably mislead multiple developers
that are using the tool without applying proper contextual escaping.

Ref: twigphp/Twig#472

Commits
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94a8655 As per twigphp/Twig#472, automatic escaping is not yet available

Author: wouterj

book/templating.rst

@@ -135,10 +135,10 @@ Throughout this chapter, template examples will be shown in both Twig and PHP.
     web designers everywhere.
 
     Twig can also do things that PHP can't, such as whitespace control,
-    sandboxing, automatic and contextual output escaping, and the inclusion of
-    custom functions and filters that only affect templates. Twig contains
-    little features that make writing templates easier and more concise. Take
-    the following example, which combines a loop with a logical ``if``
+    sandboxing, automatic HTML escaping, manual contextual output escaping, 
+    and the inclusion of custom functions and filters that only affect templates.
+    Twig contains little features that make writing templates easier and more concise.
+    Take the following example, which combines a loop with a logical ``if``
     statement:
 
     .. code-block:: html+jinja