Fix some titles, sigs in ref docs (#2128)

* Fix some title and sigs in ref docs

* better buffer source

docs/reference/game/delete.md

@@ -3,15 +3,10 @@
 Delete a sprite from the game.
 
 ```sig
-let item: game.LedSprite = null;
-item.delete();
+game.createSprite(0,0).delete()
 ```
 
-### Parameters
-
-* the **sprite** you want to delete from the game
-
-### Example
+## Example
 
 This program makes a sprite and shows the number of its brightness on the screen. Then, it deletes the sprite. 
 
@@ -21,6 +16,6 @@ basic.showNumber(ball.get(LedSpriteProperty.Brightness));
 ball.delete();
 ```
 
-### See also
+## See also
 
 [create sprite](/reference/game/create-sprite)