Link the User Guide

Readme.md

@@ -14,6 +14,8 @@ Build and publish crates with pyo3, rust-cpython and cffi bindings as well as ru
 This project is meant as a zero configuration replacement for [setuptools-rust](https://github.com/PyO3/setuptools-rust) and [milksnake](https://github.com/getsentry/milksnake).
 It supports building wheels for python 3.5+ on windows, linux, mac and freebsd, can upload them to [pypi](https://pypi.org/) and has basic pypy support.
 
+Check out the [User Guide](https://maturin.rs/)!
+
 ## Usage
 
 You can either download binaries from the [latest release](https://github.com/PyO3/maturin/releases/latest) or install it with pip: