Move text explaining API status to top of page
Move text explaining API status to top of page

The explanation of API statuses is hidden in the "Deprecated APIs"
section.  Move it to the top of the page so the status values are
explained before they're used on the page.

Change-Id: Ia32f4217f115ba74a201f89eff0e0ded56e4e16b
Closes-bug: #1778583

openstack/api-site,openstack/api-site,openstack/api-site,openstack/api-site