Check documentation in CI

[Andlon]

@Patiga suggested in #1144 that we check for broken links with cargo doc in CI. I looked through our CI config, and it looks like we are not running cargo doc at all. It seems like we should run cargo doc and fail the build if there are any substantial issues, such as broken links.

[nihonjinrxs]

Happy to put together a PR for this (though I'm still learning my way around Rust).

Are you thinking we'll want just a simple cargo doc or something more involved like cargo +nightly doc --workspace --no-deps? (The --workspace flag seems to need a nightly build and some more config based on a few minutes initial experimentation.)

[janhohenheim]

@sebcrozet pretty sure you can close this ;)