c717a70a36
rustdoc: set tab width in rust source blocks cc https://github.com/rust-lang/rust/issues/49155 (fixes it?) This sets the tab width ([in supported browsers](https://developer.mozilla.org/en-US/docs/Web/CSS/tab-size)) in Rust source blocks to 4 spaces wide (instead of the default 8), to correspond with the style guidelines.
For more information about how librustdoc
works, see the rustc guide.