Add GitHub citation file

[jmadden173]

Describe the Enhancement
Investigate and implement a citation file for the repo that references the first paper in the project. Instructions from GitHub are available here: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-citation-files

Benefits
Make the repository easier to cite and create a clear connection between published work and code repository.

Possible Drawbacks
N/A

Additional Context
Most likely will wait until first full length paper is published.