Add anchors to each header element

docs/template.html

@@ -108,8 +108,12 @@
       </div>
     </div>
 
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/1.3.0/anchor.js"></script>
     <script>
     document.addEventListener("DOMContentLoaded", function (e) {
+      anchors.options.visible = 'always';
+      anchors.add('.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4');
+
       var elements = document.querySelectorAll('table'),
           classNames = ['table', 'table-striped', 'table-hover', 'table-condensed'],
           addClass = function (el, className) {