Add config drive link to api-guide
Add config drive link to api-guide

link api-guide to doc of nova.
Removed the TODO.

Change-Id: Ib7b9453535b43e5c5cec6ee252a5790fc278f0c0

mahak/nova,phenoxim/nova,klmitch/nova,openstack/nova,klmitch/nova,mikalstill/nova,mikalstill/nova,rahulunair/nova,rahulunair/nova,mahak/nova,mahak/nova,openstack/nova,gooddata/openstack-nova,phenoxim/nova,klmitch/nova,openstack/nova,klmitch/nova,gooddata/openstack-nova,gooddata/openstack-nova,mikalstill/nova,rahulunair/nova,gooddata/openstack-nova