Fix example level spacing in README

Author: ryanb

README.md

@@ -71,11 +71,11 @@ Don't be too concerned about scoring perfectly in the beginning. After you reach
 Even though this is a text-based game, think of it as two-dimensional where you are viewing from overhead. Each level is always rectangular in shape and is made up of a number of squares. Only one unit can be on a given square at a time, and your objective is to find the square with the stairs. Here is an example level map and key.
 
 ```
-  ----
+ ----
 |C s>|
 | S s|
 |C @ |
-  ----
+ ----
 
 > = Stairs
 @ = Warrior (20 HP)