Update changelog

Author: witcher112

CHANGELOG.md

@@ -5,9 +5,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [3.9.0]
-### Changed
+### Added
 - Add support for download speed unit parameter from application info
 
+### Changed
+- Improved the network errors handling in downloaders
+
 ## [3.8.2]
 ### Added
 - Added download speed unit switcher (if download speed is higher than 1 MB/s then MB/s are used, otherwise KB/s)