Setup GitHub support for Custom Apex Domain

[SteVwonder]

The domain name is currently setup such that a visitor to pmix.org is redirected to pmix.github.io. It is possible to configure DNS and GitHub such that the content of pmix.github.io is shown but the domain name in the browser remains pmix.org.

GitHub's documentation on this: https://help.github.com/en/github/working-with-github-pages/managing-a-custom-domain-for-your-github-pages-site#configuring-an-apex-domain

AFAICT, this issue boils down two steps:

1. Add pmix.org under GitHub's "Custom Domain" option for this repo
2. Add a few A records to pmix.org's DNS

[rhc54]

Tried to do it and it failed miserably - could not create the A records on Google Domains following their instructions.