docs(examples): next proxy

https://nextjs.org/docs/pages/building-your-application/routing/api-routes
https://github.com/chimurai/http-proxy-middleware/blob/example-nextjs/recipes/servers.md#nextjs

examples/next-app/PROXY.md

@@ -0,0 +1,9 @@
+# Next.js + http-proxy-proxy
+
+See example `pages/api/users.ts`
+
+```shell
+yarn dev
+
+# visit http://localhost:3000/api/users
+```

examples/next-app/pages/api/_proxy.ts

@@ -0,0 +1,13 @@
+import type { NextApiRequest, NextApiResponse } from 'next';
+import { createProxyMiddleware } from '../../../../dist';
+
+// Singleton
+// prevent a new proxy being created for every request
+export const proxyMiddleware = createProxyMiddleware<NextApiRequest, NextApiResponse>({
+  target: 'http://jsonplaceholder.typicode.com',
+  changeOrigin: true,
+  pathRewrite: {
+    '^/api/users': '/users',
+  },
+  logger: console,
+});

examples/next-app/pages/api/users.ts

@@ -0,0 +1,21 @@
+import type { NextApiRequest, NextApiResponse, PageConfig } from 'next';
+import { proxyMiddleware } from './_proxy';
+
+// https://nextjs.org/docs/pages/building-your-application/routing/api-routes
+
+export default async function handler(req: NextApiRequest, res: NextApiResponse) {
+  return proxyMiddleware(req, res, (result: unknown) => {
+    if (result instanceof Error) {
+      throw result;
+    }
+  });
+}
+
+export const config: PageConfig = {
+  api: {
+    externalResolver: true,
+    // Uncomment to fix stalled POST requests
+    // https://github.com/chimurai/http-proxy-middleware/issues/795#issuecomment-1314464432
+    // bodyParser: false,
+  },
+};