[admin-guide] Add thread policy constraints
[admin-guide] Add thread policy constraints

'hw:cpu_thread_policy' only works if 'hw:cpu_policy' is set to
'dedicated'.

Change-Id: I545d446b5df1f47ec5e405969c31c378f83745f0

AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals