include anchor links while rendering headings

Author: onweru

layouts/_default/_markup/render-heading.html

@@ -0,0 +1,6 @@
+<h{{ .Level }} id="{{ .Anchor }}">
+  {{ .Text | safeHTML }}
+  <a href="#{{ .Anchor }}">
+  <svg xmlns="http://www.w3.org/2000/svg" fill="currentColor" width="24" height="24" viewBox="0 0 24 24"><path d="M0 0h24v24H0z" fill="none"></path><path d="M3.9 12c0-1.71 1.39-3.1 3.1-3.1h4V7H7c-2.76 0-5 2.24-5 5s2.24 5 5 5h4v-1.9H7c-1.71 0-3.1-1.39-3.1-3.1zM8 13h8v-2H8v2zm9-6h-4v1.9h4c1.71 0 3.1 1.39 3.1 3.1s-1.39 3.1-3.1 3.1h-4V17h4c2.76 0 5-2.24 5-5s-2.24-5-5-5z"></path></svg>
+  </a>
+</h{{ .Level }}>