Updated documentation about the client

Author: Nyholm

doc/customize.md

@@ -3,37 +3,34 @@
 
 ### Configure the http client
 
-Wanna change, let's say, the http client User Agent?
+Wanna change, let's say, the http client User Agent? You need to create a Plugin that modifies the
+request. Read more about [HTTPlug plugins here](http://docs.php-http.org/en/latest/plugins/introduction.html#how-it-works).
 
 ```php
-$client->getHttpClient()->setOption('user_agent', 'My new User Agent');
-```
-
-See all available options in `Github/HttpClient/HttpClient.php`
-
-### Guzzle events
-
-If you need to perform any special action on request/response use guzzle events:
-
-```php
-use Guzzle\Common\Event;
-use Github\HttpClient\Message\ResponseMediator;
+use Http\Client\Common\Plugin;
+use Psr\Http\Message\RequestInterface;
 
-$client->getHttpClient()->addListener('request.success', function(Event $event) {
-   $remaining = ResponseMediator::getApiLimit($event['response']);
+class CustomUserAgentPlugin implements Plugin
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function handleRequest(RequestInterface $request, callable $next, callable $first)
+    {
+        $request->withHeader('user-agent', 'Foobar');
 
-    var_dump($remaining);
-});
+        return $next($request);
+    }
+}
 
-$client->user()->show('cursedcoder');
+$githubClient->addPlugin(new CustomUserAgentPlugin());
 ```
 
-see list of events http://guzzle3.readthedocs.org/http-client/request.html#plugins-and-events
-
 ### Inject a new http client instance
 
-`php-github-api` provides a curl-based implementation of a http client.
-If you want to use your own http client implementation, inject it to the `Github\Client` instance:
+`php-github-api` relies on `php-http/discovery` to find an installed http client. You may specify a HTTP client
+yourself by calling `\Github\Client::setHttpClient`. A HTTP client must implement `Http\Client\HttpClient`. A list of
+community provided clients is found here: https://packagist.org/providers/php-http/client-implementation
 
 ```php
 use Github\HttpClient\HttpClient;
@@ -54,7 +51,7 @@ You can now inject your http client through `Github\Client#setHttpClient()` meth
 
 ```php
 $client = new Github\Client();
-$client->setHttpClient(new MyHttpClient());
+$client->setHttpClient(new Http\Adapter\Guzzle6\Client());
 ```
 
 ### Run Test Suite