Update docstring of 'revert_resize' function
Update docstring of 'revert_resize' function

Migrations are resizes but with the same flavor so we use the
'revert_resize' function to revert a migration also. This isn't at all
obvious though so update the docstring to highlight this fact.

Change-Id: I96bc890a28991ddee3c672fc127956ec267afea0
Signed-off-by: Stephen Finucane <492121341a95b3c3aab646bed44634f739dd019b@redhat.com>

openstack/nova,klmitch/nova,rahulunair/nova,mahak/nova,klmitch/nova,klmitch/nova,rahulunair/nova,klmitch/nova,rahulunair/nova,mahak/nova,openstack/nova,mahak/nova,openstack/nova