zaw-src-ack: hide `--group` option from user
zaw-src-ack: hide `--group` option from user

Because `--group` option is only for this source function to parse
output, there is no need to tell user is uses this option internally.

g5pw/zaw,termoshtt/zaw,junkblocker/zaw,elek/zaw,willghatch/zaw,pengjiguang/zaw,brandon-fryslie/zaw,vapniks/zaw,xeno1991/zaw