Please spell out what "references" does in @relation annotations

[tredondo]

First day with Prisma, and I'm trying to learn relations.

I get it that in author User @relation(fields: [authorId], references: [id]), the references... field (is that the correct name) is supposed to tell Prisma that the authorId field references the id field in the User model. But it would be nice to spell that out, and discuss what other values the references array can take (and why it's not written as references: id (composite keys?)

I think that belongs in the [Annotated relation fields](https://www.prisma.io/docs/orm/v6/prisma-schema/data-model/relations#annotated-relation-fields) section, which talks about fields, but not about references.