Add changelog

CHANGELOG.md

@@ -0,0 +1,22 @@
+# Changelog
+
+## 0.5
+
+* Allow specifying cached or customized merge rules.
+
+## 0.4 (2018-01-04)
+
+* Use the schema to determine the merge rules.
+* Allow specifying a custom local or remote schema.
+
+## 0.3 (2015-12-04)
+
+* Use relative imports.
+
+## 0.2 (2015-12-01)
+
+* Move repository to open-contracting organization.
+
+## 0.1 (2015-11-29)
+
+First release.