Make OAM init consistent between versions (#101)

Later revisions in the collision tutorial correct this error to be
ld [hli],a 
ld [hli],a 

If not present later, during the ball movement code the paddle bounces around the screen instead.

Author: EdHeller

unbricked/objects/main.asm

@@ -78,7 +78,7 @@ ClearOam:
 	ld [hli], a
 	ld a, 0
 	ld [hli], a
-	ld [hl], a
+	ld [hli], a
 ; ANCHOR_END: init-object
 
 ; ANCHOR: enable-oam