The help output of for zfs set/get says that sync can be one of
standard | always | disabled
but the man pages claim it can be
sync=default | always | disabled
the accepted value is standard, this changes the manpage to give the
correct values.
Signed-off-by: Steven Burgess <sburgess@dattobackup.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1634
e0fd278708