doc/radosgw: lead the orphans page with rgw-orphan-list

The page opened with the deprecated orphans find subcommands and
buried the supported replacement. Put rgw-orphan-list first and move
the deprecated material to the end for reference.

Fixes: https://tracker.ceph.com/issues/77189

Signed-off-by: Emmanuel Ameh <eameh@contractor.linuxfoundation.org>