[Samba] net rpc trustdom usage suggestion

[Karel Kulhavý]

Hello

net 3.0.2 prints out it's usage:
bash-2.05b$ net rpc trustdom
  net rpc trustdom add           add trusting domain's account
  net rpc trustdom del           delete trusting domain's account
  net rpc trustdom establish     establish relationship to trusted domain
  net rpc trustdom revoke        abandon relationship to trusted domain
  net rpc trustdom list          show current interdomain trust relationships

I suggest to add the format of the parameteres to this usage.
Let's assume net rpc trustdom add takes one parameter domain. Then the
corresponding usage line would be for example:

  net rpc trustdom add <domain>  add trusting domain's account

Cl<