add simple test data to use loaded Guzzle http client

src/index.php

@@ -0,0 +1,35 @@
+<?php
+
+require '../vendor/autoload.php';
+
+use GuzzleHttp\Client;
+use GuzzleHttp\Exception\GuzzleException;
+use GuzzleHttp\Psr7\Request;
+
+$client = new Client();
+
+try {
+    $response = $client->request('GET', 'https://api.github.com/repos/guzzle/guzzle');
+} catch (GuzzleException $e) {
+    echo $e->getMessage();
+    return;
+}
+
+echo $response->getStatusCode() . PHP_EOL;
+echo $response->getHeaderLine('content-type') . PHP_EOL;
+echo $response->getBody() . PHP_EOL;
+
+// asynchronous
+$request = new Request('GET', 'https://httpbin.org');
+
+$promise = $client
+    ->sendAsync($request)
+    ->then(function ($response) {
+        echo 'I completed! ' . $response->getBody();
+    });
+
+echo "before waiting for response" . PHP_EOL;
+
+$promise->wait();
+
+echo "after waiting for response" . PHP_EOL;