There's a a very nice guide on how to do this at https://vercel.com/guides/how-can-i-serve-multiple-projects-under-a-single-domain but all I am getting is 404 errors. Do I need more in the root domain app than a vercel.json? I can go directly to my secondary project using the internal vercel domain, but not when using the rewrite format suggested in the guide.
{ "rewrites": [ {"source": "/", "destination": "https://algae-bloom-map.vercel.app/"}, {"source": "/:match*", "destination": "https://algae-bloom-map.vercel.app/:match*"} ] }