[frameworks][examples] Add support for zero-config SvelteKit (#6482)

While we already have support for [SvelteKit](https://sveltekit-delta.vercel.app) on Vercel with the [File System API](https://vercel.com/docs/more/adding-your-framework), this makes the Svelte logo show up and adds an example. I also updated the Svelte example to match their default template and guide the user to use SvelteKit if they want functions.

https://sveltekit.examples.vercel.com

examples/sveltekit/svelte.config.js

@@ -0,0 +1,8 @@
+import vercel from '@sveltejs/adapter-vercel';
+
+export default {
+  kit: {
+    adapter: vercel(),
+    target: '#svelte',
+  },
+};