Add license and citation information

I see that most repositories under this account have a license but this one does not. Did you consider to use a license for this repository? Without one, technically no one can reuse code published on Github.
Since this project is also completed (I believe), it would also be a good addition to add a citation file. You can find information about how to add this to Github here: https://citation-file-format.github.io/
On that note, publishing to Zenodo is also worth considering for pretty much any research software as I described [here](https://github.com/UUDigitalHumanitieslab/gretel/issues/255). This of course also applies to this repository and other ones.
If you need assistance with these topics I would be happy to help.