Monetizing a git pages site by using a private repo

Currently I have a git pages site which builds from a /docs folder.

https://github.com/sdcastillo/PA-MAS-R-Study-Manual

This builds into the site http://artificialactuary.com/PA-MAS-R-Study-Manual/ (because I’ve purchased the domain name and connected this to my github account?  I’m not sure exactly why the git pages URL goes here, honestly.)

What I am looking to do is 

1.  Have users purchase access to this book.  

2.  I email add their git account to the repo, so that they can view the book and submit pull requests.

3.  Add their account

Is this something that git teams can accomplish?  I’m currently on the free plan.

@tareq111  did you meant to write something?