Explain each layout

src/grid/SpotlightExpandedLayout.tsx

@@ -23,6 +23,10 @@ import { DragCallback } from "./Grid";
 import styles from "./SpotlightExpandedLayout.module.css";
 import { useReactiveState } from "../useReactiveState";
 
+/**
+ * An implementation of the "expanded spotlight" layout, in which the spotlight
+ * tile stretches edge-to-edge and is overlaid by a picture-in-picture tile.
+ */
 export const makeSpotlightExpandedLayout: CallLayout<
   SpotlightExpandedLayoutModel
 > = ({ minBounds, pipAlignment }) => ({