Add the rtd badge

README.md

@@ -1,4 +1,5 @@
 # mmh3
+[![Documentation Status](https://readthedocs.org/projects/mmh3/badge/?version=latest)](https://mmh3.readthedocs.io/en/latest/?badge=latest)
 [![GitHub Super-Linter](https://github.com/hajimes/mmh3/workflows/Super-Linter/badge.svg?branch=master)](https://github.com/hajimes/mmh3/actions?query=workflow%3ASuper-Linter+branch%3Amaster)
 [![Build](https://github.com/hajimes/mmh3/actions/workflows/build.yml/badge.svg?branch=master)](https://github.com/hajimes/mmh3/actions/workflows/build.yml?branch=master)
 [![PyPi Version](https://img.shields.io/pypi/v/mmh3.svg?style=flat-square&logo=pypi&logoColor=white)](https://pypi.org/project/mmh3/)
@@ -13,6 +14,8 @@ Combined with probabilistic techniques like a [Bloom filter](https://en.wikipedi
 
 Another common use of mmh3 is to [calculate favicon hashes](https://gist.github.com/yehgdotnet/b9dfc618108d2f05845c4d8e28c5fc6a) used by [Shodan](https://www.shodan.io), the world's first IoT search engine.
 
+This page offers a quick start guide. For more detailed information, see the [documentation](https://mmh3.readthedocs.io/en/latest/).
+
 ## How to use
 ### Install
 ```shell