Stdpopsim: update citation in docs

[agladstein]

Docs need to be updated to cite the paper.
https://stdpopsim.readthedocs.io/en/latest/introduction.html#citations

[David-Peede]

Hi Dr. Gladstein! I have already finished steps 1 and 2 under the "Github workflow" and have done "make" in my "docs" directory. Is the next step to make a topic branch for this specific issue, edit the citation in "introduction.rst" and then submit a pull request?

[agladstein]

Yes it is!
make a topic branch, edit the citation, commit, push to your branch, and submit a pull request.

Comment here if you have any problems with it or need any more guidance.

And if something in the dev docs isn't immediately clear you can make a new issue about that so we can make them better!

[David-Peede]

Thank you so much for your guidance Dr. Gladstein! I really appreciate it!

[agladstein]

No problem!
btw, you can call me Ariella