message: docs(guides): add a link to guides in doc homepage
diff: //! Hyper provides both a [Client](client/index.html) and a
  //! [Server](server/index.html), along with a
  //! [typed Headers system](header/index.html).
  +//!
  +//! If just starting out, **check out the [Guides](https://hyper.rs/guides)
  +//! first.**
  extern crate bytes;
  #[macro_use] extern crate futures;
  