feat: copyable header anchors (fixes #86)

layouts/partials/textprocessing.html

@@ -53,4 +53,8 @@
     {{end}}
   {{end}}
 {{end}}
+
+{{/* Add copyable anchors */}}
+{{ $content = $content | replaceRE "(<h[1-9] id=\"([^\"]+)\">)(.+)(</h[1-9]>)" `<a href="#${2}">${1}<span class="hanchor" ariaLabel="Anchor"># </span>${3}${4}</a>` }}
+
 {{ $content | safeHTML }}