Added comments that need to be addressed for card draw.

Mage/src/main/java/mage/actions/MageDrawAction.java

@@ -51,6 +51,7 @@ public class MageDrawAction extends MageAction {
         int numDrawn = 0;
         int score = 0;
         GameEvent event = new DrawCardsEvent(this.player.getId(), source, this.originalDrawEvent, this.amount);
+        // TODO: This needs a better description of how it works. Why "amount < 2"?
         if (amount < 2 || !game.replaceEvent(event)) {
             amount = event.getAmount();
             for (int i = 0; i < amount; i++) {