Changelog updated for version 0.6.3

Author: remorhaz

CHANGELOG.md

@@ -4,9 +4,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.6.3] - 2019-11-18
 ### Fixed
-- Issue #3: replacing document root with `add()` fixed.
+- Issue #4: replacing document root with `add()` fixed.
 
 ## [0.6.2] - 2019-11-18
 ### Fixed