Add Zend Framework composer repository (#813)

README.md

 * [PaketHub](https://pakethub.com/) - All-in-One PHP Package Repository.
 * [Private Packagist](https://packagist.com/) - Composer package archive as a service for PHP.
 * [WordPress Packagist](https://wpackagist.org/) - Manage your plugins with Composer.
+* [Zend Framework Packages](https://packages.zendframework.com/) - Zend Framework Composer Repository.
 
 ## Dependency Management
 *Libraries for dependency and package management.*