Adding some helpful information

Author: mrkrstphr

README.md

@@ -1,2 +1,25 @@
 # wordpress-rest-api-client
-A Wordpress API client for PHP
+
+> A Wordpress REST API client for PHP
+
+For when you need to make [Wordpress REST API calls](http://v2.wp-api.org/) from
+some other PHP project, for some reason.
+
+## Installation
+
+```text
+composer require vnn/wordpress-rest-api-client
+```
+
+## Usage
+
+Example:
+
+```php
+$client = new WpClient($url);
+$client->setCredentials(new WpBasicCredentials('username', 'password'));
+
+$user = $client->users()->get(15);
+
+echo $user['username'];
+```