docs(web): JSDoc comments for svelte actions (#12963)

* Web: JSDoc comments for Actions

* Remove comment

web/src/lib/actions/intersection-observer.ts

@@ -13,7 +13,9 @@ type OnIntersectCallback = (entryOrElement: IntersectionObserverEntry | HTMLElem
 type OnSeparateCallback = (element: HTMLElement) => unknown;
 type IntersectionObserverActionProperties = {
   key?: string;
+  /** Function to execute when the element leaves the viewport */
   onSeparate?: OnSeparateCallback;
+  /** Function to execute when the element enters the viewport */
   onIntersect?: OnIntersectCallback;
 
   root?: Element | Document | null;
@@ -112,6 +114,12 @@ function _intersectionObserver(
   };
 }
 
+/**
+ * Monitors an element's visibility in the viewport and calls functions when it enters or leaves (based on a threshold).
+ * @param element
+ * @param properties One or multiple configurations for the IntersectionObserver(s)
+ * @returns
+ */
 export function intersectionObserver(
   element: HTMLElement,
   properties: IntersectionObserverActionProperties | IntersectionObserverActionProperties[],