Expand zpool-remove.8 manpage with example results

Also fix comment cross-referencing to zpool.8.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Steve Mokris <smokris@softpixel.com>
Closes #16777