rustdoc should label must_use types.

[aatxe]

Currently, the only way to know that a type is must_use is to check the source for that type. Rustdoc should probably provide some sort of label for this to make such types easier to identify. This makes the documentation more explicit.

[tomjakubowski]

Would it be sufficient to add #[must_use] to the definition (in the code block) here? http://doc.rust-lang.org/std/result/enum.Result.html

[aatxe]

Yeah, that'd be fair.