docs: update library description

Signed-off-by: Evan Sims <[email protected]>

README.md

@@ -1,17 +1,25 @@
-Lightweight PSR-7 HTTP Message implementation provider tailored to simplify mocked testing.
+**Lightweight mocking library for [PSR-7 HTTP Message](https://www.php-fig.org/psr/psr-15/) implementations, tailor-made to help you create test suites that are easier to write and maintain.**
 
 [![codecov](https://img.shields.io/codecov/c/github/psr-mock/http-message-implementation)](https://codecov.io/gh/psr-mock/http-message-implementation) [![packagist](https://img.shields.io/packagist/dt/psr-mock/http-message-implementation)](https://packagist.org/packages/psr-mock/http-message-implementation) [![status](https://img.shields.io/github/checks-status/psr-mock/http-message-implementation/1.x)]() [![license](https://img.shields.io/github/license/psr-mock/http-message-implementation)]()
 
+This library is primarily intended for use in libraries like SDKs that consume PSR implementations without requiring hard dependencies on specific libraries. The library mocks a real-world implementation and strictly adheres to PSR specifications, enabling you to create test suites that are easier to write and maintain. The library also exposes a robust developer API to help you debug and fix test failures substantially faster.
+
+This package is part of the [PSR Mock](https://github.com/psr-mock) suite of mocking libraries.
+
 ## Requirements
 
 -   PHP 8.1+
+-   Composer 2.0+
 
 ## Installation
 
 ```bash
 composer require --dev psr-mock/http-message-implementation
 ```
 
+Only install this library as a development dependency (`--dev`).
+It's not built for use in production environments.
+
 ---
 
 This library is not produced or endorsed by, or otherwise affiliated with, the PHP-FIG.