Add root static files example (#1835)

examples/root-static-files/README.md

+[![Deploy to now](https://deploy.now.sh/static/button.svg)](https://deploy.now.sh/?repo=https://github.com/zeit/next.js/tree/master/examples/custom-server)
+
+# Root static files example
+
+## How to use
+
+Download the example [or clone the repo](https://github.com/zeit/next.js):
+
+```bash
+curl https://codeload.github.com/zeit/next.js/tar.gz/master | tar -xz --strip=2 next.js-master/examples/custom-server
+cd custom-server
+```
+
+Install it and run:
+
+```bash
+npm install
+npm run dev
+```
+
+Deploy it to the cloud with [now](https://zeit.co/now) ([download](https://zeit.co/download))
+
+```bash
+now
+```
+
+## The idea behind the example
+
+This example demonstrates how to serve files such as /robots.txt and /sitemap.xml from the root.

examples/root-static-files/package.json

+{
+  "scripts": {
+    "dev": "node server.js",
+    "build": "next build",
+    "start": "NODE_ENV=production node server.js"
+  },
+  "dependencies": {
+    "next": "latest",
+    "react": "^15.5.4",
+    "react-dom": "^15.5.4"
+  }
+}

examples/root-static-files/pages/index.js

+export default () => (
+  <ul>
+    <li><a href='/robots.txt'>/robots.txt</a></li>
+    <li><a href='/sitemap.xml'>/sitemap.xml</a></li>
+    <li><a href='/favicon.ico'>/favicon.ico</a></li>
+  </ul>
+)

examples/root-static-files/server.js

+const { createServer } = require('http')
+const { parse } = require('url')
+const next = require('next')
+const { join } = require('path')
+
+const dev = process.env.NODE_ENV !== 'production'
+const app = next({ dev })
+const handle = app.getRequestHandler()
+
+app.prepare()
+.then(() => {
+  createServer((req, res) => {
+    const parsedUrl = parse(req.url, true)
+    const rootStaticFiles = [
+      '/robots.txt',
+      '/sitemap.xml',
+      '/favicon.ico'
+    ]
+    if (rootStaticFiles.indexOf(parsedUrl.pathname) > -1) {
+      const path = join(__dirname, 'static', parsedUrl.pathname)
+      app.serveStatic(req, res, path)
+    } else {
+      handle(req, res, parsedUrl)
+    }
+  })
+  .listen(3000, (err) => {
+    if (err) throw err
+    console.log('> Ready on http://localhost:3000')
+  })
+})

examples/root-static-files/static/robots.txt

+User-agent: *
+Disallow: /

examples/root-static-files/static/sitemap.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> 
+  <url>
+    <loc>http://www.example.com/foo.html</loc> 
+  </url>
+</urlset>