6. Battle Button
The battle button is controlled by an onClick. Once the button is clicked, we should display both cards that were played, and then we should call the handWinner function. Don't forget to pass the values to handWinner.
If we are to pass the cards, then really we just need to know what value is stored as the 1st card in both the user's hand and the pc's hand. Don't forget, array's don't start counting at 1.