Update Changelog for release of version 4.1.0

Author: LaunchDarklyCI

CHANGELOG.md

@@ -3,6 +3,12 @@
 
 All notable changes to the LaunchDarkly Java SDK will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org).
 
+## [4.1.0] - 2018-05-15
+
+### Added:
+- The new user builder methods `customValues` and `privateCustomValues` allow you to add a custom user attribute with multiple JSON values of mixed types. ([#126](https://github.com/launchdarkly/java-client/issues/126))
+- The new constant `VersionedDataKind.ALL` is a list of all existing `VersionedDataKind` instances. This is mainly useful if you are writing a custom `FeatureStore` implementation.
+
 ## [4.0.0] - 2018-05-10
 
 ### Changed: