Add havana/index.html file
Add havana/index.html file

Prepare for Havana launch and add an index page. It currently links
to trunk for everything, so we need to adjust this when we build
for havana.

Change-Id: I20a04864350811efbb21b11de879737f6725e2af

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