Added note on which version did dirs in group_vars start working

docsite/rst/intro_inventory.rst

@@ -180,7 +180,7 @@ Ansible will read all the files in these directories. An example with the 'ralei
 All hosts that are in the 'raleigh' group will have the variables defined in these files
 available to them. This can be very useful to keep your variables organized when a single
 file starts to be too big, or when you want to use :doc:`Ansible Vault<playbooks_vault>` on a part of a group's
-variables.
+variables. Note that this only works on Ansible 1.4 or later.
 
 Tip: In Ansible 1.2 or later the group_vars/ and host_vars/ directories can exist in either 
 the playbook directory OR the inventory directory. If both paths exist, variables in the playbook