Minor fix in role_assignments_client docstring

Change-Id: I65c7e5bd1e2f3edf90d4998f1eac01ccbedcd37f
diff --git a/tempest/lib/services/identity/v3/role_assignments_client.py b/tempest/lib/services/identity/v3/role_assignments_client.py
index c2dc3eb..10de03f 100644
--- a/tempest/lib/services/identity/v3/role_assignments_client.py
+++ b/tempest/lib/services/identity/v3/role_assignments_client.py
@@ -29,7 +29,8 @@
         http://developer.openstack.org/api-ref/identity/v3/?expanded=list-effective-role-assignments-detail
 
         :param effective: If True, returns the effective assignments, including
-                          any assignments gained by virtue of group membership.
+                          any assignments gained by virtue of group membership
+                          or inherited roles.
         """
         url = 'role_assignments'
         if kwargs: