message: Add mint rpc description
diff: @@ -2716,7 +2716,7 @@ UniValue mint(const UniValue& params, bool fHelp)
  if (fHelp || params.size() != 1)
  throw std::runtime_error(
  - "mint amount\n"
  + "mint <amount>(could not smaller than 0.1)\n"
  "\nAutomatically choose denominations to mint by amount\n" +
  HelpRequiringPassphrase());
  @@ -3155,6 +3155,7 @@ UniValue spendmanyzerocoin(const UniValue& params, bool fHelp) {
  return wtx.GetHash().GetHex();
  }
  +
  UniValue spendmany(const UniValue& params, bool fHelp) {
  if (fHelp || params.size() < 2 || params.size() > 5)
  