Update default.html

Author: mogsie

_layouts/default.html

@@ -14,7 +14,7 @@
     <meta name="twitter:label1" value="Word count"/>
     <meta name="twitter:data1" value="{{ page.content | number_of_words }}"/>
 
-    <link rel="shortcut icon" type="image/x-icon" href="favicon.ico">
+    <link rel="shortcut icon" type="image/x-icon" href="/favicon.ico">
 
     <link rel="canonical" href="https://statecharts.github.io{{ page.url }}">
     <link rel="stylesheet" type="text/css" media="screen" href="{{ '/assets/css/style.css?v=' | append: site.github.build_revision | relative_url }}">