Include file in the documentation

[Yamakaky]

It would be useful to be able a file in the documentation. My use-case is to include examples/quickstart.rs in the documentation of lib.rs. I could copy it, but it would be duplicated in the two files.

[euclio]

This would also be useful for including markdown documents in the source. For example,

#![doc(include = "README.md")]

Could avoid duplication between the main library documentation and the project's README file.

[Yamakaky]

yes!

[steveklabnik]

Duplicate of #15470, thanks!

[gilescope]

For anyone that gets here from google the answer after following the trail is now:

#![doc = include_str!("core_arch_docs.md")]

(see rust-lang/stdarch#1013 )