support highlight.js

Author: yihui

exampleSite/layouts/partials/foot_custom.html

@@ -2,3 +2,11 @@
 <script src="//cdn.jsdelivr.net/combine/npm/katex/dist/katex.min.js,npm/katex/dist/contrib/auto-render.min.js,npm/@xiee/utils/js/render-katex.js" defer></script>
 
 <script src="//cdn.jsdelivr.net/npm/@xiee/utils/js/center-img.min.js" defer></script>
+
+<script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/highlight.min.js"></script>
+<script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/languages/r.min.js"></script>
+
+<script>
+hljs.configure({languages: []});
+hljs.initHighlightingOnLoad();
+</script>

exampleSite/layouts/partials/head_custom.html

@@ -0,0 +1 @@
+<link href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/styles/github.min.css" rel="stylesheet">