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

* Web: JSDoc comments for Actions

* Remove comment

web/src/lib/actions/thumbhash.ts

@@ -1,6 +1,11 @@
 import { decodeBase64 } from '$lib/utils';
 import { thumbHashToRGBA } from 'thumbhash';
 
+/**
+ * Renders a thumbnail onto a canvas from a base64 encoded hash.
+ * @param canvas
+ * @param param1 object containing the base64 encoded hash (base64Thumbhash: yourString)
+ */
 export function thumbhash(canvas: HTMLCanvasElement, { base64ThumbHash }: { base64ThumbHash: string }) {
   const ctx = canvas.getContext('2d');
   if (ctx) {