Add esdoc documentation generator

[daniyarchambylov]

Run npm run esdoc to generate documentation in docs/ folder

[dmuhs]

Works for me and looks super neat! Under "source" in the index.html we even have documentation coverage built in, similar to here. Could we get the badge into the readme? On https://doc.esdoc.org/-/generate.html we can also build the docs if we provide an esdoc.json in our project root. Could you add this as well? From there we could probably also get the badge

[dmuhs]

Minor nitpick to link the readme badge. Apart from that, great!