title: Check if text selection is in header/footer
body: <p>The Word Addin we created allows adding custom comments to text selections. Word does not allow adding comments in headers / footers. Because of that, users should get warned when text in a header/footer is selected. </p>
  
  <ul>
  <li>The selection's OOXML structure for text in body and text in header is identical. </li>
  <li>The Word UI itself disabled the review comments section when footer/header text is selected.</li>
  <li>When dumping the text selection object to te console, none of the object fields point to the selection being in header/footer.</li>
  </ul>
  
  <p>How can be found out programmatically that text is selected in the header/footer?</p>
  
  <p>Issue: <a href="https://github.com/OfficeDev/office-js/issues/341" rel="nofollow noreferrer">https://github.com/OfficeDev/office-js/issues/341</a></p>