title: Why I can't use role="navigation" attribute in html nav tag?
body: <p>My code-snippet is below:-</p>
  
  <pre><code>&lt;nav role="navigation" data-offset-top="100" data-spy="affix" class="navbar navbar-inverse navbar-fixed-top"&gt;
  </code></pre>
  
  <p>When I validate this code, it will give me a warning, but the same code is available on bootstrap documentation.<br>
  Here is a screenshot - <a href="https://i.stack.imgur.com/WkXpL.png" rel="noreferrer"><img src="https://i.stack.imgur.com/WkXpL.png" alt="bootstrap navbar code"></a> </p>