How do I deploy a Bun repo that's in a folder using Railpack

Question

My repo has `backend` as a folder which has a bun project in there. I want to deploy it, the docs don't outline how to do this.

The monorepo doc points to a root directory option which doesn't seem to exist, and if i define a railway.json with railpack it says it can't detect what kind of project it is (how can i tell it what folder to look in?). I was excited to try railpack on this new project but looks like i am going to have to go docker again?