Add Modularity to the README.md on Pagure

[Adam Samalik]

Since the repo doesn't support PRs, could please someone add Modularity to
the readme? [1]

I've already done it [2] in my fork, but then noticed I can't submit a PR.

Thanks!
Adam

[1] https://pagure.io/fedora-docs/blob/master/f/README.md
[2]
https://pagure.io/fork/asamalik/fedora-docs/c/e5ca713aaba49a66a221e43a59716b...