Add CHANGELOG.md to document major changes (e.g. scenario renames)

Fixes #78

CHANGELOG.md

@@ -0,0 +1,58 @@
+# Changelog
+
+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]
+
+## [1.2.1] - 2023-04-18
+
+### Added
+
+- Bring back the scenarios overview map that @DamonU2 first created in October 2021
+  as there are now enough scenarios for it to be really helpful.
+
+### Changed
+
+- Rename 3 scenarios ([#77](https://github.com/OpenDRR/earthquake-scenarios/pull/77)):
+  | Old name              | New name                  |
+  | --------------------- | ------------------------- |
+  | ACM4p9_Capilano5      | ACM4p9_GeorgiaStraitFault |
+  | ACM7p4_BurwashLanding | ACM7p4_DenaliFault        |
+  | SCM5p5_Ottawa         | SCM5p5_ConstanceBay       |
+
+## [1.2.0] - 2022-10-13
+
+### Added
+
+- Four new scenarios (@jeremyrimando):
+  - ACM4p9_Capilano5
+  - ACM7p4_BurwashLanding
+  - SCM5p0_Montreal
+  - SCM5p5_Ottawa
+
+## [1.1.0] - 2022-01-27
+
+### Added
+
+- 2 new scenarios, bringing the total number of scenarios to 5:
+  - ACM7p0_GeorgiaStraitFault
+  - SCM7p5_ValDesBois
+- Create GitHub Pages (@DamonU2, @jvanulde)
+
+## [1.0] - 2021-07-06
+
+### Added
+
+- First public deterministic scenario repository release, with 3 scenarios:
+  - SIM9p0_CascadiaInterfaceBestFault
+  - ACM7p3_LeechRiverFullFault
+  - IDM7p1_Sidney
+
+[Unreleased]: https://github.com/OpenDRR/earthquake-scenarios/compare/v1.2.1...HEAD
+[1.2.1]: https://github.com/OpenDRR/earthquake-scenarios/compare/v1.2.0...v1.2.1
+[1.2.0]: https://github.com/OpenDRR/earthquake-scenarios/compare/v1.1.0...v1.2.0
+[1.1.0]: https://github.com/OpenDRR/earthquake-scenarios/compare/v1.0...v1.1.0
+[1.0]: https://github.com/OpenDRR/earthquake-scenarios/releases/tag/v1.0