update item count per game

For #17.

game/game.go

@@ -5,7 +5,7 @@
 //     It ends when the challenger wins three rounds or the dealer wins once.
 //   - A round is an instance of gameplay. Both players start each round with
 //     the same HP, and it continues until either player reaches zero.
-//   - A game is a set of 2-8 shells and 1-4 items delivered to each player.
+//   - A game is a set of 2-8 shells and 2-5 items delivered to each player.
 //     The challenger always moves first at the start of each game.
 package game
 
@@ -69,7 +69,7 @@ func (g *Match) NextRound() {
 
 // NextGame starts the next game of a round.
 func (g *Match) NextGame() {
-	items := rand.IntN(4) + 1
+	items := rand.IntN(4) + 2
 	g.players[0].startGame(items)
 	g.players[1].startGame(items)
 	shells := rand.IntN(6) + 2