I’m pretty sure the default Jekyll Pagination plugin (which is the only one of its kind currently supported by GitHub Pages) doesn’t work with paginating anything other than posts.
It also has the limitation of being used once. To do what you want you’ll need to use a different plugin. Jekyll Paginate V2 supports paginating posts, categories, tags, and collections. Only issue for you will be that it isn’t supported by GitHub Pages.
So to use it you’d have to modify how you use Jekyll with GitHub Pages and utilize some sort of deployment process.
A popular one is to build the site locally and then push the contents of your
_site folder to GH Pages. There are several ways of automating this. Another approach is to use a service like Travis CI, Netifly, and many others to manage the building and deploying of your site to GH Pages.
If talk.jekyllrb.com wasn’t wiped recently I could have pointed you to a few threads that had solutions, but instead you’ll have to resort to Googling around.