Add non-obtrusive debug info for page root

_includes/head.html

@@ -4,6 +4,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
 
     <title>{% if page.title %}{{ page.title }} | {% endif %}Go Ethereum</title>
+    <!-- debug root:{% include link.html url="/debug-path" %} -->
 
     <link rel="icon" type="image/png" href="{% include link.html url=site.favicon %}" />
     {% if layout.common-css %}

_includes/link.html

@@ -1,2 +1,2 @@
-{% capture root %}{{ page.root or site.default_root }}{% endcapture %}
+{% capture root %}{% if page.root %}{{ page.root }}{% else %}{{ site.default_root }}{% endif %}{% endcapture %}
 {{ include.url | remove: ".html" | prepend: root | replace: '//', '/' }}