Merge branch 'hotfix/delegator-invokable-example'

Fixes #191

Author: weierophinney

doc/book/delegators.md

@@ -127,12 +127,12 @@ You can then instruct the service manager to handle the service `buzzer` as a
 delegate:
 
 ```php
-use Zend\ServiceManager\Factory\InvokableClass;
+use Zend\ServiceManager\Factory\InvokableFactory;
 use Zend\ServiceManager\ServiceManager;
 
 $serviceManager = new Zend\ServiceManager\ServiceManager([
     'factories' => [
-        Buzzer::class => InvokableClass::class,
+        Buzzer::class => InvokableFactory::class,
     ],
     'delegators' => [
         Buzzer::class => [