Document workarounds for Union types #3833
Description
Union types are one of the most popular feature requests but it doesn't seem like we're adding them very soon (since they're not yet on the roadmap). There are ways though how people can workaround this and get similar functionality, one user laid these out in a comment. We should also put some documentation for such workarounds into the docs to mitigate the lack of native union type support in Prisma.
