remove aulas collection in favor of using plugin

_includes/Pages/index.html

@@ -10,7 +10,7 @@
         </div>
 
         <div class="content-box">
-            {% assign aulas = site.aulas | sort: 'date' | reverse %}
+            {% assign aulas = site.data.aulas | sort: 'date' | reverse %}
             {% assign max_aulas = 3 %}
             {% assign count = 0 %}