Remove the description of compute_api_class option
Remove the description of compute_api_class option

Since this config option has been removed long ago.

Change-Id: I40a196a63a293dc18282ae80d2b263b05f5ddd1c

rahulunair/nova,vmturbo/nova,Juniper/nova,rahulunair/nova,klmitch/nova,hanlind/nova,mahak/nova,hanlind/nova,phenoxim/nova,klmitch/nova,openstack/nova,klmitch/nova,rahulunair/nova,mikalstill/nova,Juniper/nova,rajalokan/nova,vmturbo/nova,rajalokan/nova,jianghuaw/nova,jianghuaw/nova,openstack/nova,jianghuaw/nova,gooddata/openstack-nova,phenoxim/nova,vmturbo/nova,gooddata/openstack-nova,gooddata/openstack-nova,hanlind/nova,jianghuaw/nova,klmitch/nova,Juniper/nova,gooddata/openstack-nova,mahak/nova,mikalstill/nova,Juniper/nova,rajalokan/nova,mahak/nova,openstack/nova,mikalstill/nova,vmturbo/nova,rajalokan/nova