Update README to use public released plugin (#106)

Author: Wenbing Li

README.md

@@ -1,6 +1,8 @@
-# DEVELOPER PREVIEW
+# AWS CloudFormation Resource Provider Python Plugin
 
-We're excited to share our progress with adding new languages to the CloudFormation CLI! This plugin is an early preview, and not ready for production use.
+The CloudFormation CLI (cfn) allows you to author your own resource providers that can be used by CloudFormation.
+
+This plugin library helps to provide Python runtime bindings for the execution of your providers by CloudFormation.
 
 ## AWS CloudFormation Resource Provider Python Plugin
 
@@ -13,18 +15,13 @@ This plugin library helps to provide runtime bindings for the execution of your
 Installation
 ------------
 
-Because this is a developer preview, you can't install it from pypi (the version there will not work)
-You can still install the plugin using [pip](https://pypi.org/project/pip/) from GitHub.
-
 ```bash
-pip install git+https://github.com/aws-cloudformation/aws-cloudformation-rpdk-python-plugin.git#egg=cloudformation-cli-python-plugin
+pip install cloudformation-cli-python-plugin
 ```
 
 Howto
 -----
 
-The support library, `cloudformation-cli-python-lib` must be packaged and present in the project's directory. Packaging can be done by running the `package_lib.sh` script. Example run:
-
 ```
 $ cfn init
 Initializing new project
@@ -43,7 +40,6 @@ This is highly recommended unless you are experienced
 with cross-platform Python packaging.
 >> y
 Initialized a new project in <>
-$ cp ../cloudformation-cli-python-lib-0.0.1.tar.gz .
 $ cfn submit --dry-run
 $ cat <<EOT > test.json
 {