Update scenario test readme file
Update scenario test readme file

Change-Id: I3ea9b6d0aedf69fab27745096e0314e48ce80fe6

openstack/sahara-tests,openstack/sahara-tests,esikachev/sahara-tests,openstack/sahara-scenario,esikachev/sahara-tests,openstack/sahara-scenario,esikachev/sahara-tests,openstack/sahara-scenario,openstack/sahara-tests,openstack/sahara-tests