When you setup GitHub pages, by default your content is available at https://<GITHUB_USERNAMNE>.github.io/<REPO_NAME>/.
However, if you create a repo with the exact name <GITHUB_USERNAME>.github.io, GitHub will automatically turn GitHub Pages on, and make this content avialable at https://<GITHUB_USERNAME>.github.io/. Kind of like your GitHub home page!
For example, I set up a sample at:
https://github.com/codeadamca/codeadamca.github.io
The repo is avilable as a website at:
https://codeadamca.github.io
This also works for organizations using a repo named <GITHUB_ORGANIZATION>.github.io.
For example BrickMMO has a page at:
https://brickmmo.github.io/
This setup also has the added benefit that your <GITHUB_USERNAME>.github.io website is the root of your other websites using GitHub Pages. So you can place a favicon (or other shared root files) in your <GITHUB_USERNAME>.github.io repo and it will be used by sites such as https://<GITHUB_USERNAMNE>.github.io/<REPO_NAME>/.
This GitHub Pages site uses my
favicon.icofile from mycodeadamca.github.iosite:
https://codeadamca.github.io/about-me/

I can't create a pull request, but there is a minor typo here: 😃