Added changelog (#12)

Author: Nyholm

Changelog.md

@@ -0,0 +1,25 @@
+# Change Log
+
+The change log describes what is "Added", "Removed", "Changed" or "Fixed" between each release. 
+
+## UNRELEASED
+
+## 0.2.1
+
+### Added
+
+- `TransferableStorage`
+
+### Changed
+
+- `Message` is now final
+
+## 0.2.0
+
+### Added
+
+- `Storage::create(Message $message)`
+
+## 0.1.0
+
+Init release