removing unneccessary bootstrap a11y utility reference

src/_includes/accessibility/using-with-accessibility.html

@@ -108,15 +108,6 @@
   </div>
 </div>
 
-<div class="alert alert-success">
-  <ul class="fa-ul margin-bottom-none">
-    <li>
-      <i class="fa-li fa fa-info-circle fa-lg" aria-hidden="true"></i>
-      Bootstrap comes with a <a href="http://getbootstrap.com/css/#callout-has-feedback-icon-accessibility">utility class to visually hide content, but keep it semantically accessible</a>. If you're not using Bootstrap, there are <a href="https://css-tricks.com/places-its-tempting-to-use-display-none-but-dont/">plenty</a> of <a href="https://github.com/h5bp/html5-boilerplate/blob/master/src/css/main.css#L124">recipes</a> to roll your own from.
-    </li>
-  </ul>
-</div>
-
 <div class="alert alert-success">
   <ul class="fa-ul margin-bottom-none">
     <li>