A few changes in README and add LICENSE file

[NicolasCARPi]

Hello,

This project has been part of eLabFTW since quite some time now! Thanks for putting it out there. I'll probably have to write something new when jQuery goes out the door but for now it does its job well :)

Please consider merging these few minor cosmetic changes, it's just to make the README more readable and the LICENSE file will help GitHub and others figuring out the usage conditions.

[NicolasCARPi]

Before

After

[fyneworks]

Happy to hear this little old thing has been useful 👍 Thanks for improving the formatting and adding license text.