Fix description of Auryn

It is not a container, it is an injector.

README.md

 *Libraries that implement the dependency injection design pattern.*
 
 * [Pimple](http://pimple.sensiolabs.org/) - A tiny dependency injection container.
-* [Auryn](https://github.com/rdlowrey/Auryn) - Another dependency injection container.
+* [Auryn](https://github.com/rdlowrey/Auryn) - A recursive dependency injector.
 * [Container](https://github.com/thephpleague/container) - Another flexible dependency injection container.
 * [PHP-DI](http://php-di.org/) - A dependency injection container that supports autowiring.
 * [Acclimate](https://github.com/jeremeamia/acclimate-container) - A common interface to dependency injection containers and service locators.