Add changelog

Author: phil-scale

CHANGELOG.md

@@ -4,7 +4,12 @@ All notable changes to the [Nucleus Python Client](https://github.com/scaleapi/n
 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).
 
-## [0.4.5](https://github.com/scaleapi/nucleus-python-client/releases/tag/v0.4.4) - 2021-01-07
+## [0.5.0](https://github.com/scaleapi/nucleus-python-client/releases/tag/v0.5.0) - 2021-01-10
+
+### Added
+- `nucleus.metrics` module for computing metrics between Nucleus `Annotation` and `Prediction` objects.
+
+## [0.4.5](https://github.com/scaleapi/nucleus-python-client/releases/tag/v0.4.5) - 2021-01-07
 
 ### Added
 - `Dataset.scenes` property that fetches the Scale-generated ID, reference ID, type, and metadata of all scenes in the Dataset.