docs: Improvements for domain-based routing docs and add MDX docs

[amannn]

Relevant changes:

• This PR was necessary as a prerequisite: fix: Export DomainsConfig #1175. Therefore please update next-intl to the latest version
• Move content about config.ts in routing docs out of tabs, so this is a bit more prominent (proposed docs). Note that I do think that it's currently a bit error-prone to make sure you're passing the relevant config to the middleware as well as the navigation APIs. I plan on improving the API here to have a guarantee for this (☂️ Umbrella: List of potential features / changes for a major version #779). Additionally, I might include setting up the navigation APIs in the getting started with i18n routing docs, as typically every app needs this.
• Add hint about local testing with domain-based routing (proposed docs)
• Include hint that hosting platforms typically support x-forwarded-host out-of-the-box (e.g. Vercel does this)
• Add MDX docs (proposed docs)
• Suggest alternatives when alternate links are turned off in localePrefix: 'never' docs (proposed docs)

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Name	Status	Preview	Comments	Updated (UTC)
next-intl-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 15, 2024 8:42am
next-intl-example-app-router	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 15, 2024 8:42am
next-intl-example-app-router-without-i18n-routing	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 15, 2024 8:42am

[amannn]

I'll merge this for the time being, but would be curious about feedback if you have any Maiane! :)

[sheisacreative]

Hey, Jan! 😊
Finally had some time to check everything.

My notes about it:

• DomainsConfig: tested and now it works just fine. 😊
• Move content about config.ts in routing docs out of tabs: it is not clear to me what you did here.
• Add hint about local testing with domain-based routing: love this note. I could add the header, but it is still not clear to me how this affects my project. Plus, the documentation mention Modheader, but there are some comments on chrome store saying this is a malicious tool, for this reason I used Modify Header Value instead.
• Include hint that hosting platforms typically support x-forwarded-host: nice.
• Add MDX docs: I didn't test it yet, but I read it and seems pretty clear to me. 😊
• Suggest alternatives when alternate links are turned off in localePrefix: 'never' docs: the alternatives help, but it is still not clear to me how everything works together.

Overall the improved documentation helps a lot, especially because it gives me more tips on where to find other things I need.

But, I still miss a clear path for implementing domain-based internationalization, as it seems I am gathering a lot of information from different parts of the docs and for someone who isn't an advanced developer like me, it's hard to make sense on how all those pieces work together.

Thank you for all your efforts. Count on me to help improving the docs.

Btw, I've updated the read me on my testing repository based on the new input.