[Image-guide]Add docker as one of the container formats
[Image-guide]Add docker as one of the container formats

Change-Id: I4b2b42adf0d21fb44a4b8ddab905984f5beb83fd
Closes-Bug: #1522263

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