Add second argument to union for section list layout

layouts/_default/list.html

@@ -3,7 +3,7 @@
     <!-- Any section element inside of this container is displayed as a slide -->
     <div class="slides">
       <!-- Find all pages inside of this section -->
-      {{ range union (slice .Page) }}
+      {{ range union (slice .Page) .Pages }}
       <!-- Don't process empty content files -->
         {{ if ne (len .Content) 0 }}
           <!-- Split the processed content by <hr /> tag -->