Updated the doc with python setup guide (#204)

* Update README.rst

* Update index.rst
diff --git a/docs/index.rst b/docs/index.rst
index b6dc92c..1b5f5d6 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -34,6 +34,10 @@
 google-auth is open-source, so you can alternatively grab the source code from
 `GitHub`_ and install from source.
 
+
+For more information on setting up your Python development environment, please refer to `Python Development Environment Setup Guide`_ for Google Cloud Platform.
+
+.. _`Python Development Environment Setup Guide`: https://cloud.google.com/python/setup
 .. _pip: https://pip.pypa.io
 .. _GitHub: https://github.com/GoogleCloudPlatform/google-auth-library-python