add CONTRIBUTING.md?

[ctb]

in the README you have,

If you wish to fix a bug or add new features to the software we welcome Pull Requests. Please fork the repo, make the change, then submit a Pull Request with details about what the change is and what it fixes/adds.

I'd suggest adding an explicit CONTRIBUTING.md and maybe a CoC, issue template, and PR template per suggestions here:

https://github.com/andrewjpage/tiptoft/community

See sourmash's CONTRIBUTING.md here: https://github.com/dib-lab/sourmash/blob/master/CONTRIBUTING.md - the content's more or less the same as what you have, it's just in a standardized place :)

[andrewjpage]

Thanks, I've added a contributing file, CoC and templates.