Start a changelog for version 0.4 (#143)

CHANGELOG.md

@@ -1,18 +1,23 @@
 # Changelog
 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/),
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
-### Python version support
-Support for installing and running on Python 3.10 has been added. Support for
-Python 3.7 has been dropped.
+### Changed
+- The cell detection code has been re-written to use [numba](https://numba.readthedocs.io/en/stable/) instead of Cython. This means we no longer have to pre-compile the cell detection code when making a new release of `cellfinder-core`, but does mean `numba` is now a dependency that users have to have installed. The cell detection algorithm remains the same, and perfomance has been tested to make sure it is as fast after this change.
+
+## 0.3.0 - 2022-04-25
 
 ### Added
 - Re-worked the way processes are created during the detection stage to remove
   ~20 seconds of overhead when running cell detection.
+- Support for Python 3.10.
+
+### Removed
+- Support for Python 3.7.
 
 ### Bug fixes
 - Fixed macOS issues where cellfinder could hang during the detection stage.