doc: fix syntax error in Guessing Game

Author: andreastt

src/doc/trpl/guessing-game.md

@@ -843,7 +843,7 @@ fn main() {
             Ordering::Less    => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal   => {
-                println!("You win!"),
+                println!("You win!");
                 break;
             }
         }