Hint about radosgw-admin usage
Hint about radosgw-admin usage

Added an explanation of how to use `radosgw-admin` from the Docker host to run administrative commands.
osixia/ceph-docker,CoRfr/ceph-docker,AcalephStorage/ceph-docker,fmeppo/ceph-docker,rootfs/ceph-docker,ceph/ceph-docker,osixia/ceph-docker,dmitryint/ceph-docker,cdxvirt/ceph-docker,CoRfr/ceph-docker,JrCs/ceph-docker,rootfs/ceph-docker,JrCs/ceph-docker,dmitryint/ceph-docker,osixia/ceph-docker,mkkie/ceph-docker,AcalephStorage/ceph-docker,ceph/ceph-docker,AcalephStorage/ceph-docker,dmitryint/ceph-docker,CoRfr/ceph-docker,mkkie/ceph-docker,fmeppo/ceph-docker,JrCs/ceph-docker,fmeppo/ceph-docker,cdxvirt/ceph-docker