Add errata pages to dev index.html

Author: kfranqueiro

index.html

@@ -19,6 +19,8 @@ <h1>Web Content Accessibility Guidelines {{ versionDecimal }}</h1>
     </p>
     {%- endif %}
 		<ul>
+      <li><a href="errata/21.html">Errata for 2.1</a>
+      <li><a href="errata/22.html">Errata for 2.2</a>
       {% if includeGuidelines -%}
         <li><a href="guidelines/">Guidelines</a></li>
       {%- endif %}