Add a shield with a link to the php docs

Author: jswift

README.md

@@ -5,7 +5,7 @@
 ![Packagist PHP Version Support](https://img.shields.io/packagist/php-v/aligent/bigcommerce-api-client/dev-main)
 [![License](https://img.shields.io/github/license/aligent/bigcommerce-v3-api-php-client)](https://github.com/aligent/bigcommerce-v3-api-php-client/blob/main/LICENSE.md)
 [![Build Status](https://img.shields.io/github/workflow/status/aligent/bigcommerce-v3-api-php-client/Validate%20PHP%20dependancies%20and%20test)](https://github.com/aligent/bigcommerce-v3-api-php-client/actions/workflows/php.yml)
-
+[![Documentation](https://img.shields.io/badge/docs-generated-success)](https://aligent.github.io/bigcommerce-v3-api-php-client/)
 ## Introduction
 
 This is an easy-to-use API client for [BigCommerce](https://developer.bigcommerce.com/api-reference).