title: How to add a ads.txt
body: <p>So, I want to add a ads.js to my site, but the example from Next github is not so clear. Anyone knows how to do it? 
  Here's the next example with robots and a sitemap:
  <a href="https://github.com/zeit/next.js/tree/canary/examples/with-sitemap-and-robots-express-server" rel="nofollow noreferrer">https://github.com/zeit/next.js/tree/canary/examples/with-sitemap-and-robots-express-server</a></p>
  
  <p>Thank you!</p>