title: Autocomplete Ruby on Rails form_for using HTML5 Datalist
body: <p>I have a form with text field:</p>
  
  <pre><code>&lt;%= form_for @person do |f| %&gt;
    &lt;%= f.label :first_name, "First Name" %&gt;:
    &lt;%= f.text_field :first_name %&gt;
    &lt;%= f.submit %&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>How do I use the HTML5 Datalist element to autocomplete the text field?</p>