[openstack-hpc] List suggestions

During the summit HPC discussions (https://etherpad.openstack.org/p/YVR-ops-hpc), there was a general feeling that the dedicated HPC list was not reaching a critical level and that we would attract a larger discussion base using a tag on the openstack-operators list. I would therefore propose that future HPC discussions take place on the openstack-operators list with the "[hpc]" tag in the subject line and that we close this list at the end of July. Feel free to discuss further if you feel otherwise, Tim