Merge pull request #129 from Nyholm/link-typo

Updated wrong link

Author: Nyholm

clients/includes/install-message-factory.inc

@@ -14,5 +14,5 @@ accessed through :doc:`factories </message/message-factory>`. Message factories
 
     $ composer require php-http/message
 
-.. _Diactoros: http://docs.guzzlephp.org/en/5.3/
+.. _Diactoros: https://github.com/zendframework/zend-diactoros
 .. _Guzzle PSR-7: https://github.com/guzzle/psr7