The man pages for zpool and zfs (get command)
listed the pool/dataset parameter as required,
but these are optional. Fixed that.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Gregor Kopka <gregor@kopka.net>
Closes#7916