Improve documentation for workers

[alexander-akait]

          Looks like I've solved most of the issues, the trick was to explicitly supply a true worker path as `__webpack_public_path__` and `__webpack_require__.p` inside the worker. Still needs a small blob helper to overcome the same-origin policy.

What's supported:

• cross-domain worker
• no worker loader
• sourcemaps
• dynamic import() of images and anything else

https://github.com/kirill-konshin/cross-domain-worker/blob/main/packages/cross-domain-worker/src/index.js I have published the NPM package cross-domain-worker since the solution is quite reusable.

https://github.com/kirill-konshin/cross-domain-worker/blob/main/packages/host/src/index.js usage in main thread.

https://github.com/kirill-konshin/cross-domain-worker/blob/main/packages/worker/src/worker.js usage in worker.

Originally posted by @kirill-konshin in webpack/webpack#16696 (comment)

[alexander-akait]

I think the best place here - https://webpack.js.org/guides/web-workers/

@kirill-konshin Maybe you want to help other developers and send a PR

So we will show how to build web worker in multi compiler mode + handle cross-domain + dynamic public path