Add syntax highlighting

Author: SaurabhAgarwala

.lektorproject

@@ -14,3 +14,4 @@ lektor-markdown-excerpt = 0.1
 lektor-markdown-header-anchors = 0.3.1
 lektor-strip-html-tags = 0.3.1
 lektor-webpack-support = 0.5
+lektor-markdown-highlighter = 0.3.1

configs/markdown-highlighter.ini

@@ -0,0 +1,2 @@
+[pygments]
+style = tango

templates/layout.html

@@ -5,6 +5,7 @@
 <link href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
 <link href="https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,700" rel="stylesheet"> 
 <link rel="stylesheet" href="{{ '/static/gen/style.css'|url }}">
+<link rel="stylesheet" href="{{ get_pygments_stylesheet()|url }}">
 <meta property="og:site_name" content="Creative Commons" />
 <meta property="og:title" content="{{ this.title }}" />
 {% if this.description %}