std docs should have version info and build date somewhere

[mdinger]

The std docs should list:

• The version they were built with
• The build date

They could be at the top or bottom of every page, or on a stand-alone page like About or Help.

This may not be important on rust-ci.org where I think they are rebuilt with every push but it seems like a good idea. It might be more useful on other sites where it isn't rebuilt for every push.

[Gankra]

I don't think this is a problem with std itself, since the version is in the URL (or it's master, which was built in the past 24 hours).

[mdinger]

Not sure where you mean...the std docs URL http://doc.rust-lang.org/std/ doesn't list a version. I don't think it will be a problem for Rust long-term. Once stable, the address will probably be something like http://doc.rust-lang.org/1.0/std/ with version varying between versions.

[huonw]

Partly a dupe of #14466.

[steveklabnik]

Yes, this is basically a dup of #14466/