At the very least, these types shouldn't be visible in the rustdoc.
This PR hides them from the docs, but ideally we would hide them completely from the public API (which might technically be considered a breaking change, but IMO leaking them at all is a bug).
We have a lot of backend types leaking via the public API, including e.g.
FieldElement51:https://docs.rs/curve25519-dalek/latest/curve25519_dalek/backend/serial/u64/field/struct.FieldElement51.html
At the very least, these types shouldn't be visible in the rustdoc.
This PR hides them from the docs, but ideally we would hide them completely from the public API (which might technically be considered a breaking change, but IMO leaking them at all is a bug).