Rewrites to host multiple subdomains under one domain

[ptrhck]

Following my approach facebook/docusaurus#6086 to host multiple docusaurus sites under one domain, I am trying to add the correct rewrite config to my vercel.json.

Assuming the main repo is hosted under docs.example.com. Now, I would like to rewrite the standalone docusaurus deployments ios.docs.example.com to docs.example.com/ios and android.docs.example.com to docs.example.com/android.

The idea here is that visiting docs.example.com/ios will display the content of ios.docs.example.com, e.g.
ios.docs.example.com/docs/intro -> docs.example.com/ios/docs/intro

In which project would I need to add a rewrite config and what should it look like?

[Pieparker]

In which project would I need to add a rewrite config

The one which docs.example.com/ios is attached to.

what should it look like?

Something like:

{
  "rewrites": [
    { "source": "/ios*", "destination": "https://ios.docs.example.com*" },
  ]
}

But you may need or want to tweak this to your liking.