updated link to modal window script

Created by: scottaohara

hey there,

Saw that an older version of my modal window script was linked to on this page, so I updated it to the latest version.

Thanks!

patterns/index.html

@@ -77,7 +77,7 @@ description: An accessible widget & pattern library
   <h3 class="article-section__title">Modal Windows</h3>
   <ul class="article-section__content">
     <li><a href="http://accessibility.oit.ncsu.edu/training/aria/modal-window/version-3/" rel="external">The Incredible Accessible Modal Window, Version 3</a></li>
-    <li><a href="http://codepen.io/scottohara/pen/lIdfv" rel="external">An accessible Modal Window with JavaScript & CSS</a></li>
+    <li><a href="http://scottaohara.github.io/accessible_modal_window/" rel="external">a11y Modal Window</a></li>
   </ul>
 </section>