Fixes #18 - Added �Article Metafield child resource.

Author: tareqtms

README.md

@@ -234,6 +234,7 @@ Some resources are available directly, some resources are only available through
 - [Blog](https://help.shopify.com/api/reference/blog/)
 - Blog -> [Article](https://help.shopify.com/api/reference/article/)
 - Blog -> Article -> [Event](https://help.shopify.com/api/reference/event/)
+- Blog -> Article -> [Metafield](https://help.shopify.com/api/reference/metafield)
 - Blog -> [Event](https://help.shopify.com/api/reference/event/)
 - Blog -> [Metafield](https://help.shopify.com/api/reference/metafield)
 - [CarrierService](https://help.shopify.com/api/reference/carrierservice/)

lib/Article.php

@@ -31,5 +31,6 @@ class Article extends ShopifyResource
      */
     protected $childResource = array(
         'Event',
+        'Metafield',
     );
 }