add a license

[Will Holmgren]

Thanks for sharing this interesting package. What is the license for the code? See "The Legal Side of Open Source" for why a license is needed before the community can use or modify the code.

https://opensource.guide/legal/#why-do-people-care-so-much-about-the-legal-side-of-open-source

[Martin]

Thank you for your notice, will do on the next update!

[Martin]

MIT License added