Comment 1 for bug 1331790

So, I'm trying to triage this, and found that memcached token backends can't actually delete the token.
https://bugs.launchpad.net/keystone/+bug/1290293

And, token deletion was considered an undocumented feature, since revoking tokens is really in the realm of administrators. However, the openstackclient does support it: https://review.openstack.org/#/c/95208/

I think we should document this call for completeness but there should be clarity on who can revoke (only the current user can revoke their own token? Can only an admin revoke a token?) Plus with the memcache backend issue, does it really "work?"