Merge pull request #7758 from dachary/wip-ceph-disk-prepare-help

ceph-disk: fix prepare --help

Reviewed-by: Kefu Chai <kchai@redhat.com>

src/ceph-disk/ceph_disk/main.py

@@ -1867,7 +1867,7 @@ def parser(name):
             name,
             metavar=name.upper(),
             nargs='?',
-            help=('path to OSD %s disk block device;' % name,
+            help=('path to OSD %s disk block device;' % name +
                   ' leave out to store %s in file' % name),
         )
         return parser