Changed normal link to special :phpfunction: link

Author: wouterj

reference/configuration/framework.rst

@@ -240,7 +240,7 @@ assets_version_format
 
 **type**: ``string`` **default**: ``%%s?%%s``
 
-This specifies a `sprintf()`_ pattern that will be used with the `assets_version`_
+This specifies a :phpfunction:`sprintf` pattern that will be used with the `assets_version`_
 option to construct an asset's path. By default, the pattern adds the asset's
 version as a query string. For example, if ``assets_version_format`` is set to
 ``%%s?version=%%s`` and ``assets_version`` is set to ``5``, the asset's path
@@ -372,4 +372,3 @@ Full Default Configuration
                 debug:                true
 
 .. _`protocol-relative`: http://tools.ietf.org/html/rfc3986#section-4.2
-.. _`sprintf()`: http://php.net/manual/en/function.sprintf.php