chore(example): js instead of ts for next config

Author: mudetroit

examples/nextjs/next.config.ts renamed to examples/nextjs/next.config.js

@@ -1,6 +1,4 @@
-import type { NextConfig } from "next";
-
-const nextConfig: NextConfig = {
+const nextConfig = {
   /* config options here */
   reactStrictMode: true,
 };