README.md in active_model_serializers-0.10.0

- old
+ new

@@ -25,9 +25,10 @@
 - [How to add root key](howto/add_root_key.md)
 - [How to add pagination links](howto/add_pagination_links.md)
 - [Using ActiveModelSerializers Outside Of Controllers](howto/outside_controller_use.md)
 - [Testing ActiveModelSerializers](howto/test.md)
 - [Passing Arbitrary Options](howto/passing_arbitrary_options.md)
+- [How to serialize a Plain-Old Ruby Object (PORO)](howto/serialize_poro.md)
 
 ## Integrations
 
 | Integration | Supported ActiveModelSerializers versions |  Gem name and/or link
 |----|-----|----