[The Book, Translations] fixed domain cascading doc

lerouquin · lerouquin · commit 86c432e056a5 · 2013-07-14T13:24:24.000+02:00
diff --git a/book/translation.rst b/book/translation.rst
@@ -493,6 +493,9 @@ you must specify the domain as the third argument of ``trans()``::
 Symfony2 will now look for the message in the ``admin`` domain of the user's
 locale.
 
+.. versionadded:: 2.4
+    Support for translation domain cascading was added in Symfony 2.4.
+
 In some cases, you may need a fallback mechanism: you can also provide an
 array of domains instead:
 
