readme.md: typo (#100)

Author: grogy

readme.md

@@ -177,7 +177,7 @@ $container = new $class;
 and then use container to create object `NewsletterManager` and we can send e-mails:
 
 ```php
-$manager = $container->getByType('NewsletterManager');
+$manager = $container->getByType(NewsletterManager::class);
 $manager->distribute(['[email protected]', ...]);
 ```