Added leading slash in URL

Same here, otherwise it will throw an error because it cant find the fetch URL path

site/content/tutorial/04-logic/06-await-blocks/app-b/App.svelte

@@ -2,7 +2,7 @@
 	let promise = getRandomNumber();
 
 	async function getRandomNumber() {
-		const res = await fetch(`tutorial/random-number`);
+		const res = await fetch(`/tutorial/random-number`);
 		const text = await res.text();
 
 		if (res.ok) {