Add LICENSE file

[davelab6]

I suggest adding a LICENSE file to this repo with the Apache or MIT license; Apache has better US Patent protections, but MIT is used in other repos in this org.

(I noticed a couple of MIT license files have different copyright author notices)

• https://github.com/EasyEyes/remote-calibrator/blob/main/LICENSE
• https://github.com/EasyEyes/virtual-keypad/blob/main/LICENSE

(Similar to EasyEyes/Easyeyes-Analyzer#2)