Hides dispay of grandchildren

Display of grandchildren links in the navigation is now delayed until their parent is selected.

To test, select the `Grandchildren test` node. Only the direct children should appear. Selecting one of them then shows its children.

_includes/nav.html

@@ -10,6 +10,7 @@
             {%- endif -%}
             <a href="{{ node.url | absolute_url }}" class="navigation-list-link{% if page.url == node.url %} active{% endif %}">{{ node.title }}</a>
             {%- if node.has_children -%}
+            {%- if page.url == node.url or page.parent == node.title or page.grand_parent == node.title -%}
               {%- assign children_list = site.html_pages | where: "parent", node.title | sort:"nav_order" -%}
               <ul class="navigation-list-child-list ">
                 {%- for child in children_list -%}
@@ -19,6 +20,7 @@
                     {%- endif -%}
                     <a href="{{ child.url | absolute_url }}" class="navigation-list-link{% if page.url == child.url %} active{% endif %}">{{ child.title }}</a>
                     {%- if child.has_children -%}
+                      {%- if page.url == child.url or page.parent == child.title -%}
                         {%- assign grand_children_list = site.html_pages | where: "parent", child.title | sort:"nav_order" -%}
                         <ul class="navigation-list-child-list">
                         {%- for grand_child in grand_children_list -%}
@@ -26,12 +28,14 @@
                             <a href="{{ grand_child.url | absolute_url }}" class="navigation-list-link{% if page.url == grand_child.url %} active{% endif %}">{{ grand_child.title }}</a>
                           </li>
                         {%- endfor -%}
-                      </ul>
+                        </ul>
+                      {%- endif -%}
                     {%- endif -%}
                   </li>
                 {%- endfor -%}
               </ul>
             {%- endif -%}
+            {%- endif -%}
           </li>
         {%- endif -%}
       {%- endunless -%}

docs/grandchildren-test/buttons.md

+---
+layout: default
+title: Buttons
+parent: Grandchildren test
+has_children: true
+---
+
+Buttons
+----
+
+Child of [Grandchildren test](..)

docs/grandchildren-test/buttons/grandchild.md

+---
+layout: default
+title: Buttons Child Page
+parent: Buttons
+grand_parent: Grandchildren test
+---
+
+Buttons Child Page
+----

docs/grandchildren-test/index.md

+---
+layout: default
+title: Grandchildren test
+has_children: true
+nav_order: 8
+---
+
+Grandchildren test
+==================
+
+Has a child [Buttons](buttons)
+and a grandchild [Child of Buttons](buttons/grandchild)

docs/grandchildren-test/labels.md

+---
+layout: default
+title: Labels
+parent: Grandchildren test
+has_children: true
+---
+
+Labels
+----
+
+Child of Grandchildren test

docs/grandchildren-test/labels/label-grandchild.md

+---
+layout: default
+title: Labels Child Page
+parent: Labels
+grand_parent: Grandchildren test
+---
+
+Labels Child Page
+----