Add bonus round image

slides/bonus.md

@@ -1,5 +1,5 @@
-## Bonus Round!
-
+## Bonus Round! <!-- .element: class="text-over-image" -->
+<!-- .slide: data-background="slides/bonus_round.jpg" data-background-size="contain" data-background-opacity="0.3"-->
 -V-
 
 ### Journal