Add license information

[vazhnov]

Hello!

I found link to this project from https://robertoostenveld.nl/art-net-to-dmx512-with-esp8266/

Could you please add information about license of this repository — is it allowed to copy, change and use code in any purpose?
It would be great to see any popular open source license.

[robertoostenveld]

Hi @vazhnov,

The code that I wrote and/or collected in this repository is mostly a mash-up of code snippets and information that I found at various places on the internet. There are pieces where I am not even sure if I could be considered the original author. For the pieces of code here in which I invested more substantial (creative) efforts, I am happy to share back to the community without restrictions. So please consider it to be in the public domain, i.e. you can do with it what you want. See https://fairuse.stanford.edu/overview/public-domain/welcome/.

Note that this does not apply to the Arduino core, applications, or any libraries that might be used by the code in this repository; those are covered by their respective licenses.

best regards,
Robert

[vazhnov]

@robertoostenveld , could you please add a note into README.md, for example create chapter "License" and copy your text above?

Also, please, take a look at cc0, maybe it is a better description of what you want.

[robertoostenveld]

With cc0 I would claims rights as being the creator, which is not appropriate in some cases. Hence I think that https://en.wikipedia.org/wiki/Public_domain is more suited to describe the situation.

I added something to the readme.