Add nova-cert to the compute getstart
Add nova-cert to the compute getstart

An introduction to the nova-cert module was missing
from the compute introduction. This adds an entry to the
list for it.

Change-Id: I3e805ed953d27a48e007e2776ae37205726704d6
Closes-Bug: 1160757

potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,kairoaraujo/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,kairoaraujo/openstack-manuals,saeki-masaki/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,Akasurde/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals