Hide instructions when reached 2048

[Crystal-RainSlide]

If the player (like me...) reaches 2048 within the first time when he open this app, the instructions still won't go away, and at that point, he should - no longer need it.

Related code:

2048/2048/base/src/main/java/com/tpcstld/twozerogame/MainView.java

Line 435 in ae2df47

if (showHelp) drawInstructions(canvas);