Consider adding a LICENSE file

It seems that this piece of software is advertised as an [Open Source](https://opensource.org/osd) software. However, there exists no indication about the distribution and modification allowances of the project, neither some that follows the open source philosophy.

For this reason, I strongly encourage adding an Open Source license to the project, by adding a file named `LICENSE` at the root, which contains the chosen license.

A list of open source licenses as defined by the OSD can be found at .