Create CHANGELOG.md (#180)

* Create CHANGELOG.md

* Update CHANGELOG.md

CHANGELOG.md

@@ -0,0 +1,54 @@
+# Changelog
+All notable changes to Constellation 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
+- CLI
+  - Command `constellation recover` to re-initialize a completely stopped cluster.
+  - Command `constellation config generate` to generate a default configuration file for a specific cloud provider.
+- CSI
+  - Option to enable dm-integrity in a StorageClass.
+  - Support volume expansion.
+  - Support volume snapshots.
+- Option to add SSH users on init.
+
+### Changed
+- CLI UX
+  - `constellation create` now requires a configuration file. The usual workflow is to run `constellation config generate` first.
+  - Consistent command format with at most one argument and named flags otherwise.
+  - Display usage when invalid arguments are passed.
+  - Add list of instance types to command help.
+  - Wording tweaks.
+- CLI config
+  - Rename dev-config to config.
+  - Change format to YAML.
+  - Make it self-documenting.
+  - Validation.
+  - Rename *PCRs* to *Measurements*.
+
+### Removed
+- Support for non-CVMs on GCP.
+
+### Fixed
+- Pin Kubernetes version deployed by `kubeadm init`.
+
+### Security
+- Replace single, never expiring Kubernetes join token with expiring unique tokens.
+- Apply CIS benchmark for kubeadm clusterconf and kubelet conf.
+- Enable Kubernetes audit log.
+
+### Internal
+- Create GCP images in `constellation-images` project so that they can be shared with customers.
+- Add customer onboarding docs.
+- Add E2E test as Github Action.
+- Improvements to local QEMU testing.
+- Preparations for mutual ATLS.
+
+## [1.0.0] - 2022-04-28
+Initial release of Constellation. With underlying WireGuard and Kubernetes compliant.
+
+[Unreleased]: https://github.com/edgelesssys/constellation/compare/v1.0.0...HEAD
+[1.0.0]: https://github.com/edgelesssys/constellation/releases/tag/v1.0.0