Fix typo in api-ref doc
Fix typo in api-ref doc

Change-Id: I67c390d20bbdc016c44b4c9cd187f5ddde649768

openstack/keystone,ilay09/keystone,rajalokan/keystone,ilay09/keystone,rajalokan/keystone,mahak/keystone,mahak/keystone,ilay09/keystone,openstack/keystone,openstack/keystone,rajalokan/keystone,mahak/keystone