message: Add link to book to the readme.
diff: @@ -7,7 +7,9 @@ A statistics-driven micro-benchmarking library.
  This is a port of [Haskell's criterion][haskell] library.
  -# [Documentation][docs]
  +# [Getting Started][start]
  +# [User Guide][guide]
  +# [API Documentation][docs]
  # License
  @@ -15,5 +17,7 @@ criterion.rs is dual licensed under the Apache 2.0 license and the MIT license.
  See LICENSE-APACHE and LICENSE-MIT for more details.
  -[docs]: http://japaric.github.io/criterion.rs/criterion/
  +[docs]: https://japaric.github.io/criterion.rs/criterion/
  +[guide]: https://japaric.github.io/criterion.rs/book/index.html
  +[start]: https://japaric.github.io/criterion.rs/book/getting_started.html
  [haskell]: https://hackage.haskell.org/package/criterion
  