Adds a comment to the compute.image module proposed in [1] providing
context on where the values were derived from, and that they should be
kept in sync in the (perhaps unlikely) event that more image types are
added in the future.
[1] I2a76e6b1062b0112faec73cef4a369124e45aa98
Change-Id: I1f0d79e3e77d23d3a190bad594c504ef5503cc67
These are traits used to represent Glance image types that may be supported
by a service such as nova-compute. Glance defines these types rigidly in
their documentation:
https://docs.openstack.org/image-guide/image-formats.html#disk-formats
and thus they should be stable and standardized for use in placement
queries.
Change-Id: I2a76e6b1062b0112faec73cef4a369124e45aa98