* Update manpage with more information about the ACL, guest access
  and that samba needs to be able to authenticate user(s).
* Add information that 'net' can be used to modify the share after
  ZFS sharing and that it will be undone with a 'zfs unshare'.
Closes: #1181

* Do basic sanity checks in smb_available() to verify that the 'net'
  command and the usershare directory exists.
Closes: #1124

* Give an example on how to mount a SMB filesystem shared via ZFS.
Improves: #1170