Please specify the license

[yeldarby]

Hi, thanks for open sourcing this project. We're hoping to use this plugin in one of our projects but we were unable to determine the license. Could you add a LICENSE file to the repo to clarify how it may be used?

If you haven't given it consideration yet, having the same MIT license as Pixi itself would be preferred; otherwise there's more info about various licenses here: https://choosealicense.com