CHANGELOG: add CHANGELOG.md

add a draft of the changelog for containerd-shim-wasm following the
https://keepachangelog.com/en/1.1.0/ format. The changelog starts from
the v0.15.1 release to HEAD. it is expected that the future PRs will
update the CHANGELOG.md with the changes made.

Signed-off-by: jiaxiao zhou <[email protected]>

Author: Mossaka

CHANGELOG.md

@@ -0,0 +1,30 @@
+# Changelog
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased] - YYYY-MM-DD
+
+### Added
+
+- Added MQTT trigger and tests ([#175](https://github.com/spinkube/containerd-shim-spin/pull/175))
+- Make container environment bariables accessible as application variables ([#149](https://github.com/spinkube/containerd-shim-spin/pull/149))
+- Added feature to conditionally restart the k0s controller service when present during node installation. ([#167](https://github.com/spinkube/containerd-shim-spin/pull/167))
+
+### Changed
+
+- Updated the minimum required Rust version to 1.79 ([#191](https://github.com/spinkube/containerd-shim-spin/pull/191))
+- Refactored the shim code by splitting it into different modules ([#185](https://github.com/spinkube/containerd-shim-spin/pull/185))
+- Refactored the Makefile to improve its structure and comments([#171](https://github.com/spinkube/containerd-shim-spin/pull/171))
+- Merged two Redis trigger test apps into one ([#176](https://github.com/spinkube/containerd-shim-spin/pull/176))
+- Simplified the run command in the documentation ([#184](https://github.com/spinkube/containerd-shim-spin/pull/184))
+-  Modified Dependabot settings to group patch-level dependency updates ([#162](https://github.com/spinkube/containerd-shim-spin/pull/162))
+
+### Fixed
+
+- Correct currently supported triggers ([#182](https://github.com/spinkube/containerd-shim-spin/pull/182))
+- Fixed an error in `setup-linux.sh` script ([#184](https://github.com/spinkube/containerd-shim-spin/pull/184))
+- Updated outdated links to `spinkube.dev` ([#170](https://github.com/spinkube/containerd-shim-spin/pull/170))
+
+---
+
+[Unreleased]: https://github.com/spinkube/containerd-shim-spin/compare/v0.15.1...HEAD