Add changelog

Author: infctr

CHANGELOG.md

@@ -0,0 +1,12 @@
+# 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/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.9.0] - 2020-05-19
+
+### Added
+
+- New option to `interface` rule: `requiredFirst` - if `true`, enforce optional properties to come after required ones.