Update existing explanation about compute
Update existing explanation about compute

Update an explanation in admin-guide-cloud
with more details.

Co-Authored-By: Thiago Gomes <1a87ef62d3058308fc1ea157288760de9464f698@lsbd.ufc.br>
Closes-Bug: #1456032
Change-Id: I4c1f2cddda83ea45e88ab2781610530dad2bf512

kairoaraujo/openstack-manuals,openstack/openstack-manuals,Akasurde/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,kairoaraujo/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,Akasurde/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals