Added multi-region/multi-cloud use case to specs
Added multi-region/multi-cloud use case to specs

Change-Id: I3b5bcbb8f41c987b421303a72aa010e520b9439f

sajuptpm/magnum,Alzon/SUR,ChengTiesheng/magnum,paulczar/magnum,jay-lau/magnum,paulczar/magnum,ffantast/magnum,sajuptpm/magnum,ArchiFleKs/magnum,LaynePeng/magnum,annegentle/magnum,dimtruck/magnum,Tennyson53/SUR,Tennyson53/SUR,ramielrowe/magnum,eshijia/SUR,mjbrewer/testindex,ffantast/magnum,hongbin/magnum,eshijia/magnum,Alzon/SUR,openstack/magnum,eshijia/SUR,openstack/magnum,annegentle/magnum,mjbrewer/testindex,ddepaoli3/magnum,dimtruck/magnum,Tennyson53/magnum,ddepaoli3/magnum,ramielrowe/magnum,Tennyson53/magnum,ChengTiesheng/magnum,eshijia/magnum,mjbrewer/testindex,ArchiFleKs/magnum,hongbin/magnum,LaynePeng/magnum