update head

Author: githubdingyun

_includes/head.html

@@ -6,6 +6,8 @@
     <meta name="description" content="{{ site.description }}">
     <meta name="keywords"  content="{{ site.keyword }}">
     <meta name="theme-color" content="{{ site.chrome-tab-theme-color }}">
+	<meta name="referrer" content="no-referrer"/>
+
 
     <!-- Open Graph -->
     <meta property="og:title" content="{% if page.title %}{{ page.title }} - {{ site.SEOTitle }}{% else %}{{ site.SEOTitle }}{% endif %}">