Fixed comment in example code showing how to map the service name AuthorizationInterface to a factory

Author: arueckauer

docs/book/v1/auth-adapter.md

@@ -31,7 +31,7 @@ following ways:
 
   return [
       'dependencies' => [
-          // Using an alias:
+          // Using a factory:
           'factories' => [
               AuthorizationInterface::class => ZendAclFactory::class,
           ],