Host a non-#[doc(hidden)] Rust documentation for contributors

[hlbarber]

We use #[doc(hidden)] extensively in the rust-runtime crates to allow for APIs to be public to the code generated code but not public to the general consumer to avoid semver constraints - if somethings #[doc(hidden)] we can change its API without the risk of breaking customer code.

This poses a problem for writing documentation for contributors however - docs are not able to point a link to a hosted document which contains API descriptions.

Compiling our own documentation in CI using

RUSTDOCFLAGS='-Z unstable-options --document-hidden-items' cargo +nightly doc

and then hosting it would remedy this.

In both the hidden and unhidden cases, having a link to the hosted documentation in the README.md would be beneficial.

As an additional side effect, we would also be able to catch broken doc links, lints, etc in CI. Running cargo doc in rust-runtime reveals 3 lints, running RUSTDOCFLAGS='-Z unstable-options --document-hidden-items' cargo +nightly doc reveals 50+.

[Velfi]

Personally, I'd rather direct contributors to build the docs themselves using those options. I do agree that being able to find broken doc links would be beneficial.

[jdisanti]

We use #[doc(hidden)] extensively in the rust-runtime crates to allow for APIs to be public to the code generated code but not public to the general consumer to avoid semver constraints

We no longer do this since it turns out the semver constraints are still there even with doc hidden. Going to resolve this since docs can also be built locally.