Enforce https:// on modcluster.io and update links

This server could not prove that it is modcluster.io; its security certificate is from *.github.com. This may be caused by a misconfiguration or an attacker intercepting your connection.

[4:46 PM] Radoslav Husar: The custom domain for your GitHub Pages site is pointed at an outdated IP address. You must update your site's DNS records if you'd like it to be available via your custom domain. For more information, see https://help.github.com/articles/setting-up-a-custom-domain-with-github-pages/.
[4:47 PM] Radoslav Husar: Enforce HTTPS — Unavailable for your site because your domain is not properly configured to support HTTPS (modcluster.io) — Troubleshooting custom domains

https://help.github.com/articles/troubleshooting-custom-domains/#https-errors