Update README.md

Author: Josh Holtz

README.md

@@ -10,6 +10,7 @@ A library for loading data from a [JSON API](http://jsonapi.org) datasource. Par
 
 Version | Changes
 --- | ---
+ **1.0.4** | Add support for empty to-one relationship according to JSON API v1.0 (https://github.com/joshdholtz/jsonapi-ios/pull/33). Thanks to [RafaelKayumov](https://github.com/RafaelKayumov) for helping!
 **1.0.3** | Add ability to map different types of objects (https://github.com/joshdholtz/jsonapi-ios/pull/32). Thanks to [ealeksandrov](https://github.com/ealeksandrov) for helping!
 **1.0.2** | Just some bug fixes. Thanks to [christianklotz](https://github.com/christianklotz) for helping again!
 **1.0.1** | Now safely checks for `NSNull` in the parsed JSON. Thanks to [christianklotz](https://github.com/christianklotz) for that fix!