Add license

[haesleinhuepf]

Hi all,

fantastic repository! Great that you are sharing it open source! I was just wondering under which conditions one could reuse the materials provided here, e.g. for teaching courses and therefore resharing your materials. Would you mind adding a license file? If you're new to licensing and/or wonder which license to use, you can read more in this blog post: https://focalplane.biologists.com/2023/05/06/if-you-license-it-itll-be-harder-to-steal-it-why-we-should-license-our-work/

Thanks!

Best,
Robert