Add Section Header Anchor Links

Author: maennchen

docs/_includes/head-custom.html

@@ -1,4 +1,12 @@
 <script type="text/javascript" src="{{ '/assets/js/randomize-order.js?v=' | append: site.github.build_revision | relative_url }}"></script>
+
+<script type="text/javascript" src="{{ '/assets/js/anchor.min.js?v=' | append: site.github.build_revision | relative_url }}"></script>
+<script>
+document.addEventListener("DOMContentLoaded", function() {
+  anchors.add()
+});
+</script>
+
 <style>
   .sponsors {
     display: flex;

docs/assets/js/anchor.min.js

@@ -6,19 +6,19 @@ Here you can find documents and other resources produced by the Security WG of t
 
 We welcome feedback and suggestions, especially to public drafts: please open an issue or PR through our [GitHub repo](https://github.com/erlef/security-wg). You can reach out to members of the working group through the [#security](https://the-eef.slack.com/archives/CTP7P1E9X) channel at the [EEF Slack workspace](https://erlef.org/slack-invite/erlef), or via email at security (at) erlef (dot) org.
 
-# Documents
+## Documents
 
 * [Secure Coding and Deployment Hardening Guidelines](secure_coding_and_deployment_hardening)
 * [Web Application Security Best Practices for BEAM languages](web_app_security_best_practices_beam)
 * [Security Vulnerability Disclosure](security_vulnerability_disclosure)
 * [Meeting Notes](https://erlangforums.com/t/security-working-group-minutes/3451)
 
-# Specifications
+## Specifications
 
 * 'hex' Package URL type
     * Part of [Hex specifications](https://github.com/hexpm/specifications/blob/master/package-url.md)
 * ['otp' Package URL type](specs/otp_purl_type) (draft)
 
-# Initiatives
+## Initiatives
 
 * [Ægis Supply Chain Security & Compliance Initiative](aegis)