Update Changelog for release of version 6.6.0

Author: LaunchDarklyCI

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to the LaunchDarkly Python SDK will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org).
 
+## [6.6.0] - 2018-11-14
+### Added:
+- It is now possible to inject feature flags into the client from local JSON or YAML files, replacing the normal LaunchDarkly connection. This would typically be for testing purposes. See `file_data_source.py`.
+
 ## [6.5.0] - 2018-10-17
 ### Added:
 - The `all_flags_state` method now accepts a new option, `details_only_for_tracked_flags`, which reduces the size of the JSON representation of the flag state by omitting some metadata. Specifically, it omits any data that is normally used for generating detailed evaluation events if a flag does not have event tracking or debugging turned on.