Refactor note layout to remove unnecessary tags

Author: mlmstdt

_layouts/note.html

@@ -1,8 +1,6 @@
+---
 layout: default
 ---
-
-<article class="article-page">
-  {% include article-header.html %}
-  {% include article-body.html %}
-  {% include apparatus.html notes=page.notes %}
-</article>
+{% include article-header.html %}
+{% include article-body.html %}
+{% include apparatus.html notes=page.notes %}