etcdctl: Documment downgrade commands
etcdctl: Documment downgrade commands

rnaveiras/etcd,etcd-io/etcd,mqliang/etcd,mkumatag/etcd,mkumatag/etcd,etcd-io/etcd,rnaveiras/etcd,ajityagaty/etcd,ajityagaty/etcd,mqliang/etcd,mqliang/etcd,mkumatag/etcd,rnaveiras/etcd,etcd-io/etcd,ajityagaty/etcd