I followed the steps below to point my root domain
zean.be and the custom subdomain
www.zean.be to a GitHub Pages project.
Step 1: configure your GitHub Pages project to accept requests from your custom domains.
Create a file called CNAME in the root directory with the following two entries (with
zean.be replaced by your own domain),
These two entries tell GitHub to redirect any requests to USERNAME.github.io to the domain specified in the CNAME file.
Step 2: add DNS records to point your root domain/subdomain to GitHub.
Add the following CNAME record to your DNS provider,
www.zean.be CNAME USERNAME.github.io
and add the following A records for the root domain,
@ A 18.104.22.168 @ A 22.214.171.124 @ A 126.96.36.199 @ A 188.8.131.52