Update includdes

Author: hschne

_layouts/default.html

@@ -51,7 +51,7 @@
             Conferences
           </a>
         </nav>
-        <nav class="toc toc--sticky" aria-label="Guide contents"><p class="toc__heading">Contents</p><!--toc--></nav>
+        {% include toc.html variant="toc--sticky" heading="Contents" %}
       </div>
     </div>
     {% endif %}

_layouts/guide.html

@@ -6,7 +6,7 @@
   <article class="guide-content">{{ content }}</article>
 
   {% if page.toc %}
-  <nav class="toc toc--desktop" aria-label="Guide contents"><!--toc--></nav>
+  {% include toc.html variant="toc--desktop" %}
   {% endif %}
 </div>