Default to /static/
If can be useful to change it to / when hosting robots.txt or sitemap.xml
Also move the serveStatic logic for the folder inside lib/nuxt.js, so the middleware will have the same logic.
<!--cmty--><!--cmty_prevent_hook--><div align="right"><sub><em>This feature request is available on <a href="https://nuxtjs.cmty.io">Nuxt.js</a> community (<a href="https://nuxtjs.cmty.io/nuxt/nuxt.js/issues/c2">#c2</a>)</em></sub></div>