Fix ZoomableTileMap data.geojson

Author: techniq

packages/layerchart/src/routes/docs/examples/ZoomableTileMap/+page.ts

@@ -1,7 +1,8 @@
 import pageSource from './+page.svelte?raw';
 
-export async function load() {
+export async function load({ fetch }) {
   return {
+    geojson: (await fetch('https://cdn.jsdelivr.net/npm/us-atlas@3/counties-10m.json')).json(),
     meta: {
       pageSource,
     },