Document: with_file(glob) relative path and roles

Document that with_file and with_fileglob path is relative to
the files directory inside of a role.

docsite/latest/rst/playbooks.rst

@@ -438,6 +438,8 @@ inside another.
    play are going to get the same tasks.  ('*when*' provides some
    ability for hosts to conditionally skip tasks).
 
+.. _roles:
+
 Roles
 `````
 

docsite/latest/rst/playbooks2.rst

@@ -467,6 +467,12 @@ be used like this::
           with_file:
              - /home/foo/.ssh/id_rsa.pub
 
+.. note::
+
+   When using ``with_fileglob`` or ``with_file`` with :ref:`roles`, if you
+   specify a relative path (e.g., :file:`./foo`), Ansible resolves the path
+   relative to the :file:`roles/<rolename>/files` directory.
+
 .. versionadded: 0.9
 
 Many new lookup abilities were added in 0.9.  Remeber lookup plugins are run on the *controlling* machine::