Add a changelog entry for #902

Author: dmitry-timofeev

exonum-java-binding/CHANGELOG.md

@@ -26,6 +26,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 - `BinaryTransactionMessage#toString` to include some fields in human-readable
  format instead of the whole message in binary form.
+- RocksDB library is no longer required to be installed on Mac or Linux to run
+ the Exonum Java application. (#902)
 
 ## [0.6.0]- 2019-05-08