Exceptions for setting html_root_url and documentation to docs.rs

[dtolnay]

The main one I know of is docs.rs only supports documenting the default feature set: https://github.com/onur/docs.rs/issues/29.

Dependency on system libraries may also be a problem.

[dtolnay]

Some points against docs.rs in https://github.com/onur/docs.rs/issues/125#issuecomment-301208170.

[onur]

Since https://github.com/onur/docs.rs/pull/131 docs.rs is automatically setting html_root_url for crates and it's dependencies. I think C-HTML-ROOT can be removed from rust-api-guidelines.

Also docs.rs now supports building non-default features.

[dtolnay]

I removed the html_root_url guideline in 5c457df and the docs.rs guideline in b7a831e.

[CAD97]

Why was C-HTML-ROOT was re-added in b36cc0d? It seems that it's not needed anymore. Should it just be re-removed now?

[dtolnay]

It still makes a difference for cargo doc --no-deps local builds. Without it, rustdoc doesn't link to types from your crate.