bug #5058 Fix: assets_version instead of asset_version (sebastianblum)

This PR was submitted for the 2.6 branch but it was merged into the 2.3 branch instead (closes #5058).

Discussion
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Fix: assets_version instead of asset_version

The name of the function is assets_version, see
https://github.com/symfony/symfony/blob/2.7/src/Symfony/Bundle/TwigBundle/Extension/AssetsExtension.php

Commits
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40363c9 Fix: assets_version instead of asset_version

reference/twig_reference.rst

@@ -116,12 +116,12 @@ Returns a public path to ``path``, which takes into account the base path set
 for the package and the URL path. More information in
 :ref:`book-templating-assets`.
 
-asset_version
-~~~~~~~~~~~~~
+assets_version
+~~~~~~~~~~~~~~
 
 .. code-block:: jinja
 
-    {{ asset_version(packageName) }}
+    {{ assets_version(packageName) }}
 
 ``packageName``
     **type**: ``string`` | ``null`` **default**: ``null``