minor #7900 add app.flashes() to the Twig reference (xabbuh, javiereguiluz)

This PR was merged into the master branch.

Discussion
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add app.flashes() to the Twig reference

see #7808 (comment)

Commits
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b626c3e Minor typo
e066653 add app.flashes() to the Twig reference

Author: javiereguiluz

reference/twig_reference.rst

@@ -738,6 +738,7 @@ The available attributes are:
 * ``app.debug``, a boolean telling whether the debug mode is enabled in the app;
 * ``app.token`` (a :class:`Symfony\\Component\\Security\\Core\\Authentication\\Token\\TokenInterface`
   object representing the security token)
+* ``app.flashes``, returns flash messages from the session
 
 .. _`Twig Reference`: http://twig.sensiolabs.org/documentation#reference
 .. _`Twig Extensions repository`: https://github.com/twigphp/Twig-extensions