Update the Concepts' nav bar.

Author: Martin Taillefer

_includes/doc-side-concepts-nav.html

@@ -3,7 +3,6 @@
 	<li><h5 class="doc-side-nav-title">Concepts</h5></li>
 	<li class="doc-side-nav-list-item"><a href="{{ site.baseurl }}/docs/concepts/what-is-istio.html" {% if current[3] == 'what-is-istio.html' %}class='current'{% endif %}>What is Istio?</a></li>
 	<li class="doc-side-nav-list-item"><a href="{{ site.baseurl }}/docs/concepts/service-model.html" {% if current[3] == 'service-model.html' %}class='current'{% endif %}>Service Model</a></li>
-	<li class="doc-side-nav-list-item"><a href="{{ site.baseurl }}/docs/concepts/attributes.html" {% if current[3] == 'attributes.html' %}class='current'{% endif %}>Attributes</a></li>
 
 	<li class="submenu">
 		<h6 class="arrow-r">Network and Auth</h6>
@@ -12,6 +11,7 @@ <h6 class="arrow-r">Network and Auth</h6>
 	<li class="submenu">
 		<h6 class="arrow-r">Policies and Control</h6>
 		<div class="submenu-content">
+			<a class="submenu-link {% if current[3] == 'attribute.html' %}active{% endif %}" href="{{ site.baseurl }}/docs/concepts/attributes.html">Attributes</a>
 			<a class="submenu-link {% if current[3] == 'mixer.html' %}active{% endif %}" href="{{ site.baseurl }}/docs/concepts/mixer.html">Mixer</a>
 			<a class="submenu-link {% if current[3] == 'mixer-config.html' %}active{% endif %}" href="{{ site.baseurl }}/docs/concepts/mixer-config.html">Mixer Configuration</a>
 		</div>