Comment 1 for bug 1625260

I'm not sure what needs updating in the admin guide for this, I already see this:

http://docs.openstack.org/admin-guide/compute-flavors.html

Disk: "Virtual root disk size in gigabytes. This is an ephemeral disk that the base image is copied into. When booting from a persistent volume it is not used. The “0” size is a special case which uses the native base image size as the size of the ephemeral root volume."