Link to "Initial research on the wiki" in README.md is dead

[zetok]

https://github.com/rust-lang/rust/wiki/Lib-datetime redirects to https://github.com/rust-lang/rust

[lifthrasiir]

Oh, the wiki is now (somehow) dead. I assume the page is now at https://github.com/rust-lang/rust-wiki-backup/blob/master/Lib-datetime.md, thank you for noticing that.