message: docs(lib): mention reqwest in docs homepage
diff: //!
  //! If just starting out, **check out the [Guides](https://hyper.rs/guides)
  //! first.**
  +//!
  +//! If looking for just a convenient HTTP client, consider the
  +//! [reqwest](https://crates.io/crates/reqwest) crate.
  extern crate bytes;
  #[macro_use] extern crate futures;
  