As skins is html and already parsed for liquid finally we can set the doc root correctly

Signed-off-by: Hofi <hofione@gmail.com>

Author: HofiOne

_includes/skins.html

@@ -23,8 +23,7 @@
 
 <script async="false">
 
-  // FIXME: How to get the real base URL (without using Liquid and Front Matter) ?!?!
-  const docRoot = '';
+  const docRoot = '{{ site.baseurl }}';
   const darkSkin = 'midnight';
   const lightSkin = 'default';