developer-roadmap/pages/roadmaps.js

import DefaultLayout from 'layouts/default/index';
import PageHeader from 'components/page-header/index';

const RoadmapsList = () => (
  <DefaultLayout>
    <PageHeader />
    <div className="container">
      <p>Show all roadmaps here</p>
    </div>
  </DefaultLayout>
);

export default RoadmapsList;