Update README.md with gameplay rules

See #1.

README.md

@@ -1,6 +1,24 @@
 # Short Circuit, created at #DroidconHack15
 Created by [Andrew Jack](https://twitter.com/andr3wjack), [Sam Parkinson](https://twitter.com/samparkinson_), [Laith Nurie](https://twitter.com/laith_nurie), [Ted Eriksson](https://twitter.com/Ted_Eriksson)
 
+A NFC enabled card game about battery drain. 1 to 4 players.
+
+### Setup
+
+* Shuffle the deck and place it face down within reach of all players
+* Each player should be dealt one card
+* The player with the lowest battery goes first
+
+### Gameplay
+
+* Draw a card from the top of the deck
+* Play a card from your hand, then add it to a discard pile
+* When there are no more cards, or there is only 1 player left with a charge the round ends
+
+The winner is the player with the most charge remaining.
+
+Tap cards on the battery that should be affected.
+
 ## Setting up Google Play Services Nearby
 Follow [this](https://developers.google.com/nearby/messages/android/get-started) guide to obtain a API key for the nearby API. Once obtained add it to the manifest file.