message: op-chain-ops: add comment to lwd -> xdm
diff: @@ -172,7 +172,8 @@ func (w *LegacyWithdrawal) Value() (*big.Int, error) {
  }
  // CrossDomainMessage turns the LegacyWithdrawal into
  -// a CrossDomainMessage
  +// a CrossDomainMessage. LegacyWithdrawals do not have
  +// the concept of value or gaslimit, so set them to 0.
  func (w *LegacyWithdrawal) CrossDomainMessage() *CrossDomainMessage {
  return &CrossDomainMessage{
  Nonce: w.Nonce,
  