[docs] fix path to /tutorial/image.gif (#7033)

site/content/examples/00-introduction/01-dynamic-attributes/App.svelte

@@ -1,5 +1,5 @@
 <script>
-	let src = 'tutorial/image.gif';
+	let src = '/tutorial/image.gif';
 	let name = 'Rick Astley';
 </script>
 

site/content/tutorial/01-introduction/03-dynamic-attributes/app-a/App.svelte

@@ -1,5 +1,5 @@
 <script>
-	let src = 'tutorial/image.gif';
+	let src = '/tutorial/image.gif';
 </script>
 
 <img>

site/content/tutorial/01-introduction/03-dynamic-attributes/app-b/App.svelte

@@ -1,5 +1,5 @@
 <script>
-	let src = 'tutorial/image.gif';
+	let src = '/tutorial/image.gif';
 	let name = 'Rick Astley';
 </script>