Add an example for update in object_usage
Add an example for update in object_usage

This is a followup from [1]. which missed
the example for update and get_object.

[1]. https://review.openstack.org/336518

Change-Id: I0cc91e3070bd466bcccbdb2bcd4505a24924884f

mahak/neutron,eayunstack/neutron,huntxu/neutron,openstack/neutron,eayunstack/neutron,noironetworks/neutron,huntxu/neutron,openstack/neutron,mahak/neutron,mahak/neutron,noironetworks/neutron,openstack/neutron