improve v2 docs

docs/v2/next-app/next.config.js

@@ -1,10 +0,0 @@
-/** @type {import('next').NextConfig} */
-const nextConfig = {
-  reactStrictMode: true,
-  swcMinify: true,
-  images: {
-    unoptimized: true,
-  },
-};
-
-module.exports = nextConfig;

docs/v2/next-app/next.config.mjs

@@ -0,0 +1,34 @@
+import mdx from '@next/mdx';
+import rehypePrettyCode from 'rehype-pretty-code';
+import rehypeSlug from 'rehype-slug';
+import remarkGfm from 'remark-gfm';
+
+/** @type {import('next').NextConfig} */
+const withMDX = mdx({
+  extension: /\.mdx?$/,
+  options: {
+    remarkPlugins: [remarkGfm],
+
+    rehypePlugins: [
+      rehypeSlug,
+      [
+        rehypePrettyCode,
+        {
+          theme: 'solarized-light',
+        },
+      ],
+    ],
+    providerImportSource: '@mdx-js/react',
+  },
+});
+
+const nextConfig = {
+  reactStrictMode: true,
+  swcMinify: true,
+  images: {
+    unoptimized: true,
+  },
+  pageExtensions: ['js', 'jsx', 'ts', 'tsx', 'md', 'mdx'],
+};
+
+export default withMDX(nextConfig);