Improve documentation

[aitorllj93]

I think this beautiful library should have a good documentation as well. Right now, many links on the readme are failing, the npm package doesn't have readme at all and you usually need to dig deep into the source code to read the examples and node descriptions in order to be able to properly work with it. I would improve the Readme and add a documentation website (thinking about docusaurus) with all the examples available. I think this would be a great improvement on the library overall.

@bhouston if you agree I can start working on it

[bhouston]

please do! Be aware that this is an implementation that is helping to drive the glTF interactivity extension: https://github.com/ux3d/glTF/blob/00606e5d654c0c319c274250f3505e70e05d6102/extensions/2.0/Khronos/KHR_behavior/README.md. You can find additional documentation there. It is sort of an eventual consistency model between this library and that extension.

[aitorllj93]

@bhouston working on it, hope to have an initial PR for today or tomorrow and we can discuss about some details when it's ready