Added vercel to self-hosting.mdx

[anubhav1206]

No description provided.

[ergomake]

Hi 👋

Here's a preview environment 🚀

https://front-twentyhq-twenty-1049.env.ergomake.link

Environment Summary 📑

Container	Source	URL
front	Dockerfile	https://front-twentyhq-twenty-1049.env.ergomake.link
server	Dockerfile	https://server-twentyhq-twenty-1049.env.ergomake.link
postgres	Dockerfile	[not exposed - internal service]

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[FelixMalfait]

Hey @anubhav1206 thanks for giving it a shot! Unfortunately, I don't think it's going to work out of the box like that.
I've never used Vercel so I'm not sure it's possible to achieve what we were able to achieve with Render.
But basically we should pass Vercel commands to let them know how to build and run the front/backend.
And if some things cannot be managed through the Vercel button (e.g. provisioning Postgres?) then we'd need to give instructions in the README on appropriate steps to take

If you have never used Vercel, this issue might be a bit complex to handle.
I'll close the PR for now but feel free to reopen a new one anytime!