message: Add comment for the change script
diff: @@ -2866,6 +2866,8 @@ bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend, CWalletTx& wt
  // send change to existing address
  if(fNotUseChangeAddress)
  {
  + // setCoins will be added as inputs to the new transaction
  + // Set the first input script as change script for the new transaction
  auto pcoin = setCoins.begin();
  scriptChange = pcoin->first->tx->vout[pcoin->second].scriptPubKey;
  }
  