Update changelog

Author: pcothenet

CHANGELOG.md

@@ -5,6 +5,13 @@ 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).
 
+## [1.6.0] - 2021-07-14
+
+### Added
+
+- Order responses return a `registry_url` field
+- Add support for Bitcoin estimates
+
 ## [1.5.2] - 2021-03-30
 
 ### Changed