Add LICENSE.md

[jimkoen]

Hey!
Hate to be that guy to ask for a license, but it would clarify how other people can look into and use this code.

I'm currently looking into playing around with Blackfin DSP's and to have a license would be really cool,
since then I know wether I'm allowed to reuse code 😅 Wether it's MIT, GPL2/3, idc, just any license would be great :)

Btw this is a really cool project and I'm hoping that more people that are into music production realize how much
an open source community about digital hardware synthesizers would benefit them.

Anyways, kind regards and merry Christmas^^

EDIT: I just saw the video of your synth bass, as well as your blackfin-arduino library and I am absolutely stunned. This is insane. Like I can't even put it to words.
I'm not sure if your plan was to ever release parts of your software as open source, but I am begging you to open source your projects, I don't care under what license, just please please please add one. I see this as a one of kind learning opportunity, as well as open source opportunity to finally replace monopoles on small HW synths like the OP-1.