Automated documentation translations — Dutch + updated Chinese demo

Hi @mweststrate — I noticed you co-initiated zh.mobx.js.org for MobX and Immer already has a zh-CN locale. We'd love to help expand and maintain that automatically.

We're PageTurner — we automatically translate open-source documentation and keep translations in sync via CI/CD. Currently maintaining translations for 87 projects. Here's a live demo for Immer:

• Dutch: immer.page-turner.com/nl/ — you can evaluate quality in your native language
• Chinese (simplified): immer.page-turner.com/zh-Hans/

The existing zh-CN translation was great community work, but it's ~3 years behind (missing array-methods, v11 changes). Our translations stay current automatically.

If this looks good to you, we can also add Japanese, Korean, Spanish, and French — Korean was requested in #535 but never delivered. With ~27M weekly downloads, these languages would open up Immer to a much wider audience.

How it works: We transfer a translation repo to the immerjs org. You own it. We maintain contributor access and push updates automatically. Zero maintenance, zero cost, no lock-in — revoke our access anytime.

I can submit a PR adding the i18n config and locale dropdown — you'd just need to merge.

Review the existing zh-CN translation and the proposed transfer of a translation repository to the immerjs organization. Then assess the requested i18n configuration and locale dropdown, including Dutch and updated Chinese support. Done would require an agreed translation scope and maintainer approval for the integration approach.