[docs] UV-THREADPOLL-SIZE may not be needed anymore

[feychou]

https://github.com/kununu/nukleus/blob/master/docs/package.json#L62-L63

This was a hack that I added at the very start in order to force the compilation of the sass style. For reference check out this discussion webpack-contrib/sass-loader#100

It is possible that reducing the style size and updating to new version of node-sass or sass-loader, this hack is not necessary anymore.

Just try to remove the variable and check if the compilation goes through anyway.