import Helmet from 'react-helmet'
import Markdown from 'react-markdown'

import Layout from '../components/Layout'
import Mock from '../components/Mock'
import Footer from '../components/Footer'
import Page from '../components/Page'

export default ({ url }) => <Layout url={url}>
    <Page>
      <Helmet title="About" />
      <article>
        <h1>This site is under construction...</h1>
      </article>
    </Page>
  </Layout>

import Helmet from 'react-helmet'
import Markdown from 'react-markdown'

import Layout from '../components/Layout'
import Mock from '../components/Mock'
import Footer from '../components/Footer'
import Page from '../components/Page'

export default ({ url }) => <Layout url={url}>
    <Page>
      <Helmet title="About" />
      <article>
        <h2>This site is under construction...</h2>
      </article>
    </Page>
  </Layout>

Update about.js