added changelog

CHANGELOG.md

@@ -0,0 +1,16 @@
+Change Log
+=======
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+## [Unreleased]
+
+## [v0.1.0]
+
+### Added
+
+- First version of the PAC which builds. Uses a patched version
+  of `svd2rust`: https://github.com/rust-embedded/svd2rust