code: function toRoute (pageDir, entry) {
    const page = '/' + relative(pageDir, entry)
    let base = page.split(extname(page)).join('')
    if (base[0] === '/') {
      base = base.substring(1)
    }
    if (base === 'index') {
      const dir = dirname(page)
      return dir + base
    } else {
      return '/' + base
    }
  }
docs: Turn the path into a route  e.g. - index.js        => / - about.js        => /about - movies/index.js => /movies