Update changelog

Author: jeffsmale90

packages/smart-accounts-kit-x402/CHANGELOG.md

@@ -1,3 +1,14 @@
 # Changelog
 
-All notable changes to `@metamask/smart-accounts-kit-x402` will be documented in this file.
+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).
+
+## [Unreleased]
+
+### Added
+
+- New @metamask/smart-accounts-kit-x402 package providing plugins to @x402 packages ([#236](https://github.com/MetaMask/smart-accounts-kit/pull/236))
+
+[Unreleased]: https://github.com/metamask/smart-accounts-kit/