Switch website from Netlify to to GitHub Pages

[kgjenkins]

I have a "ghpages" branch that will build the website using GitHub Pages instead of using Netlify, viewable here:
https://openindexmaps.github.io/

@thatbudakguy There are still a few CSS issues (link colors, code style, and spacing) that need to be addressed. Once those are worked out (comparing to the Netlify version currently at https://openindexmaps.org/), we can get rid of Netlify and point the domain to GH Pages.