Updated readme

Signed-off-by: Bastian Schwarz <bastian@repareo.de>

Author: Bastian Schwarz

README.md

@@ -8,8 +8,41 @@
 ![Packagist Downloads](https://img.shields.io/packagist/dt/codenamephp/deploymentchecks.http)
 ![GitHub](https://img.shields.io/github/license/codenamephp/deploymentchecks.http)
 
+This package provides simple checks for http services. It can check if a service is reachable and if it returns a specific status code, response body, ...
+
 ## Installation
 
 Easiest way is via composer. Just run `composer require codenamephp/deploymentchecks.http` in your cli which should install the latest version for you.
 
-## Usage
+You should also explicitly install the `codenamephp/deploymentchecks.base` package since you will end up using it directly in almost all cases.
+
+## Usage
+
+Just create checks, pass them to a collection and run them:
+
+```php
+use de\codenamephp\deploymentchecks\base\Check\Collection\SequentialCheckCollection;
+use de\codenamephp\deploymentchecks\base\Check\Result\Collection\ResultCollection;
+use de\codenamephp\deploymentchecks\http\HttpCheckResult;
+use de\codenamephp\deploymentchecks\http\RunTestsOnHttpResponse;
+use de\codenamephp\deploymentchecks\http\Test\CssSelectorExists;
+use de\codenamephp\deploymentchecks\http\Test\Result\HttpTestResult;
+use de\codenamephp\deploymentchecks\http\Test\StatusCode;
+use GuzzleHttp\Psr7\Request;
+
+$check = new SequentialCheckCollection(new RunTestsOnHttpResponse(
+  new Request('GET', 'https://localhost/test.html'),
+  'Exists',
+  new StatusCode(200),
+),
+  new RunTestsOnHttpResponse(
+    new Request('GET','https://localhost/404.html'),
+    'Does not exist',
+    new StatusCode(404),
+  ),
+);
+
+$result = $check->run();
+
+exit($result instanceof WithExitCodeInterface ? $result->exitCode() : ($result->successful() ? DefaultExitCodes::SUCCESSFUL->value : DefaultExitCodes::ERROR->value));
+```