Update release notes

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -50,6 +50,8 @@ Project: jackson-databind
 #4570: Deprecate `ObjectMapper.canDeserialize()`/`ObjectMapper.canSerialize()`
 #4580: Add `MapperFeature.SORT_CREATOR_PROPERTIES_BY_DECLARATION_ORDER` to use
   Creator properties' declaration order for sorting
+#4584: Provide extension point for detecting "primary" Constructor for Kotlin
+  (and similar) data classes
 #4602: Possible wrong use of _arrayDelegateDeserializer in
   BeanDeserializerBase::deserializeFromObjectUsingNonDefault()
  (reported by Eduard G)