Updates to api-specs.html to add new Compute Extensions book
Updates to api-specs.html to add new Compute Extensions book

Change-Id: I7ba95a674a3c41991c1438bd8494b9abe2faf5a0
author: Diane Fleming

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