title: AMP: The mandatory tag 'html ⚡ for top-level html' is missing or incorrect
body: <p>I am getting the following error from Google Webmaster Tools for AMP:</p>
  
  <blockquote>
    <p>The mandatory tag 'html ⚡ for top-level html' is missing or incorrect.</p>
  </blockquote>
  
  <p>How can I fix this issue?</p>