Updated Readme To List Changes from Amazon

Based upon feedback here: #13 (review)

Signed-off-by: Justin Yost <[email protected]>

README.md

@@ -8,7 +8,18 @@ This repository contains the open source PHP SDK that allows you to access the [
 
 ## Copy of Amazon's Provided Code
 
-This is a public copy of [Amazon's provided code](https://webservices.amazon.com/paapi5/documentation/quick-start/using-sdk.html), as their version is not available through Packagist as of writing.
+This is a near identical public copy of [Amazon's provided code](https://webservices.amazon.com/paapi5/documentation/quick-start/using-sdk.html), as their version is not available through Packagist as of writing.
+
+We have not changed the API in any way, however we did cleanup portions of the code and have updated dependencies. A listing of changes are provided below.
+
+### Changes from Amazon
+
+* Replaced usage of `\GuzzleHttp\Psr7\build_query` with `\GuzzleHttp\Psr7\Query::build` https://github.com/thewirecutter/paapi5-php-sdk/pull/8
+* Added Support for Guzzle 7 https://github.com/thewirecutter/paapi5-php-sdk/pull/6
+* Removed Deprecation Warnings when using PHP 8 https://github.com/thewirecutter/paapi5-php-sdk/pull/13
+* Updated PHP Minimum Version to PHP 8 https://github.com/thewirecutter/paapi5-php-sdk/pull/13
+* CodeSniffed to PSR-2 https://github.com/thewirecutter/paapi5-php-sdk/pull/13
+* Updated Dev Dependencies to reflect PHP 8 version requirement https://github.com/thewirecutter/paapi5-php-sdk/pull/13
 
 ## Installation
 The Product Advertising API PHP SDK can be installed with [Composer](https://getcomposer.org/). The SDK is available via [Packagist](http://packagist.org/) under the [`thewirecutter/paapi5-php-sdk`](https://packagist.org/packages/thewirecutter/paapi5-php-sdk) package. If Composer is installed globally on your system, you can run the following in the base directory of your project to add the SDK as a dependency: