Add license information

[vazhnov]

Hello!

I found this project from https://saveitforparts.wordpress.com/2023/03/29/a-cheap-and-relatively-easy-microwave-imager-radiotelescope/ (which I found from https://hackaday.com/2023/03/31/see-satellites-in-broad-daylight-with-this-sky-mapping-dish-antenna/ ).

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