:art: Add cover image

README.md

@@ -2,6 +2,8 @@
 
 A small multi-ball breakout game where accuracy is required.
 
+![Kace cover image](cover.png)
+
 ## Game description
 
 Aim, shoot and combo! Try to high-score before you are overwhelmed by bricks! Each time a ball hits, the brick life amount is decreased by one, and you get a score point. When the brick is destroyed, you get a new ball for the following rounds until you loose. Each round, a new row of bricks is generated. So, aim wisely and try to maximize shoot efficiency!