Create addScenePopHandler.md

Author: DeveloperTryingToCodeLikeOtherOfThem

docs/reference/game/addScenePopHandler.md

@@ -0,0 +1,14 @@
+## addScenePopHandler
+Registers a handler that runs whenever a scene is popped onto the scene stack.
+
+## Parameters
+handler: the code that runs
+
+## Example
+Set a new background color (blue) when the scene has popped.
+``` ts
+    game.popScene();
+    game.addScenePopHandler(() => {
+        scene.setBackgroundColor(8);
+    });
+```