[www] update sitemap.xml
[www] update sitemap.xml

Change-Id: I8ddaf18667d29a65ae4cd242163b0756285c6a1a
Partial-Bug: #1591717

openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals