Remove navigation role as it is unnecessary

_includes/_navigation.html

@@ -3,7 +3,7 @@
 		<a href="{{ site.url }}/">{{ site.title }}</a>
 	</div><!-- /.site-name -->
 	<div class="top-navigation">
-		<nav role="navigation" id="site-nav" class="nav">
+		<nav id="site-nav" class="nav">
 		    <ul>
 		        {% for link in site.data.navigation %}
 				    {% if link.url contains 'http' %}
@@ -16,4 +16,4 @@
 		    </ul>
 		</nav>
 	</div><!-- /.top-navigation -->
-</div><!-- /.navigation-wrapper -->
+</div><!-- /.navigation-wrapper -->