add changelog

Author: wickerpopstar

CHANGELOG.md

@@ -0,0 +1,20 @@
+## 2.0.0
+- Breaking Changes:
+  - Several model renames for more precise mapping to controllers
+  - Remove shipping callback related models
+- New Features:
+  - Transaction Search API
+  - Subscriptions API
+- Bug Fixes:
+  - Fix deprecated descriptions not properly reflecting on the SDK
+  - Fixes issues related to Network Transaction Reference not parsing properly
+  - Various bug fixes
+
+## 1.1.0
+- Added new models to support Apple Pay, Google Pay
+- Expanded models to support additional optional fields
+- Bug fixes
+- Documentation updates
+
+## 1.0.0
+- GA Release for Orders, Payments, and Vault APIs