Added example to documentation

Author: GeeH

doc/book/config-abstract-factory.md

@@ -32,7 +32,8 @@ Configuration is done through the `config` service manager key, in an array with
 the key `Zend\ServiceManager\AbstractFactory\ConfigAbstractFactory`. If you are using 
 config merging from the MVC/ModuleManager, in this just means that you can 
 add a `ConfigAbstractFactory::class` key to your merged config which contains service
-definitions:
+definitions, where the key is the service name (typically the FQNS of the class you are 
+defining), and the value is an array of it's dependencies, also defined as container keys.
 
 ```php
 use Zend\ServiceManager\AbstractFactory\ConfigAbstractFactory;
@@ -57,3 +58,49 @@ call with that key on the service manager it is attached to. In this way, you ca
 correct tree of dependencies to successfully return any given service. Note that `Handler` does not have a 
 configuration for the abstract factory, but this would work if `Handler` had a traditional factory and 
 can be created by this service manager.
+
+For a better example, consider the following classes:
+
+```php
+class UserMapper
+{
+    public function __construct(Adapter $db, Cache $cache) {}
+}
+
+class Adapter
+{
+    public function __construct(array $config) {}
+}
+
+class Cache
+{
+    public function __construct(CacheAdapter $cacheAdapter) {}
+}
+
+class CacheAdapter
+{
+}
+```
+
+In this case, we can define the configuration for these classes as follows:
+
+```php
+// config/autoload/dependencies.php or anywhere that gets merged into global config
+return [
+    ConfigAbstractFactory::class => [
+        CacheAdapter::class => [], // no dependencies
+        Cache::class => [
+            CacheAdapter::class, // dependency on the CacheAdapter key defined above
+        ],
+        UserMapper::class => [
+            Adapter::class, // will be called using normal factory defined below
+            Cache::class, // defined above and will be created using this abstract factory
+        ],
+    ],
+    'service_manager' => [
+        'factories' => [
+            Adapter::class => AdapterFactory::class, // normal factory not using above config
+        ],
+    ],    
+],
+```

doc/book/tmp.php

@@ -0,0 +1,20 @@
+<?php
+
+class UserMapper
+{
+    public function __construct(Adapter $db, Cache $cache) {}
+}
+
+class Adapter
+{
+    public function __construct(array $config) {}
+}
+
+class Cache
+{
+    public function __construct(CacheAdapter $cacheAdapter) {}
+}
+
+class CacheAdapter
+{
+}