Update RELEASE-NOTES.md

[skip ci]

Author: JeroenDeDauw

RELEASE-NOTES.md

@@ -5,7 +5,8 @@
 * Removed `Claims` class (deprecated since 1.0)
 * Removed `getClaims` and `setClaims` from `Entity`, `Item` and `Property` (deprecated since 1.0)
 * Removed `ReferenceList::removeDuplicates`
-* `ReferenceList` no longer derives from `SplObjectStorage`, though now implements `Countable` and `IteratorAggregate`
+* `ReferenceList` no longer derives from `SplObjectStorage`, though still implements `Countable`
+    * `ReferenceList` now implements `IteratorAggregate` and has a `toArray` method
 * Removed `HashableObjectStorage`
 
 ## Version 4.4.0 (2016-01-20)