Add debug

_includes/directory-tree.html

@@ -17,6 +17,9 @@
   strong      Wrap a <strong> tag around titles of the pages that have `strong: true` in the Front Matter.
               Default: false.
 {%- endcomment -%}
+layout=<pre>{{ include | inspect }}</pre>
+layout=<pre>{{ page | inspect }}</pre>
+layout=<pre>{{ layout | inspect }}</pre>
 {%- unless include.li or page.directory-tree.li or layout.directory-tree.li %}<ul>{%- endunless %}
   {%- assign dir_class = include.dir_class  | default: page.directory-tree.dir_class | default: layout.directory-tree.dir_class -%}
   {%- if dir_class -%}