refactor: we standardize on adoc for changelogs

CHANGELOG.adoc

+:issues: https://git.fitko.de/fit-connect/planning/-/issues
+
+[comment]
+--
+Types of changes:
+
+- Added: for new features.
+- Changed: for changes in existing functionality.
+- Deprecated: for soon-to-be removed features.
+- Dependencies: for changed / updated dependencies.
+- Removed: for now removed features.
+- Fixed: for any bug fixes.
+- Security: in case of vulnerabilities.
+
+Don't forget to tag @ https://git.fitko.de/fit-connect/event-payload/-/tags
+--
+
+== Changelog: SET Payload Schema
+
+* The format is based on https://keepachangelog.com/en/1.1.0/[Keep a Changelog], and this project adheres to https://semver.org/spec/v2.0.0.html[Semantic Versioning].
+* If available, include a ticket number in format `(planning#XXXX)`.
+
+=== [Unreleased] - YYYY-MM-DD
+
+=== [1.2.1] - 2024-01-08
+
+==== Added
+
+* Defined new events in context of the implementation of bidirectional communication {issues}/460[`(planning#460)`]
+** `create-reply` event documenting a Reply has been appended. Authored by the Zustelldienst.
+** `submit-reply` event documenting a Reply has been submitted. Authored by the Zustelldienst.
+** `notify-reply` event documenting the Onlineservice knows of the Reply. Authored by the Zustelldienst.
+** `reject-reply` event documenting a Reply has been rejected. Authored by the Zustelldienst.
+** `accept-reply` event documenting a Reply has been accepted. Authored by the Zustelldienst.
+** `delete-reply` event documenting a Reply has been deleted. Authored by the Zustelldienst.
+
+==== Deprecated
+
+* Event `forward-submission` is now deprecated and {issues}/310[will be removed in a future release]. {issues}/1292[`(planning#1292)`]
+
+=== [.line-through]#[1.2.0] - 2024-01-05# *superseded by [1.2.1]*
+
+Do not use this release.
+
+=== [1.1.0] - 2023-05-20
+
+==== Changed
+
+* Allow `$schema` to have versions. {issues}/608[`(planning#608)`]
+
+=== [1.0.0] - 2022-01-05
+
+* Baseline changelog.
+  Check GIT history for a changelog of this and earlier versions.

CHANGELOG.md

-<!--
-Types of changes:
-  - Added: for new features.
-  - Changed: for changes in existing functionality.
-  - Deprecated: for soon-to-be removed features.
-  - Removed: for now removed features.
-  - Fixed: for any bug fixes.
-  - Security: in case of vulnerabilities.
--->
-
-# Event-Payload Changelog
-
-* The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
-* If available, include a ticket number in format `(planning#XXXX)`.
-
-## Unreleased
-
-## [1.2.0]
-
-### Added
-
-- defined new events in context of the implementation of bidirectional communication [`(planning#460)`](https://git.fitko.de/fit-connect/planning/-/issues/460)
-  - `create-reply` event documenting a Reply has been appended. Authored by the Zustelldienst.
-  - `submit-reply` event documenting a Reply has been submitted. Authored by the Zustelldienst.
-  - `notify-reply` event documenting the Onlineservice knows of the Reply. Authored by the Zustelldienst.
-  - `reject-reply` event documenting a Reply has been rejected. Authored by the Zustelldienst.
-  - `accept-reply` event documenting a Reply has been accepted. Authored by the Zustelldienst.
-  - `delete-reply` event documenting a Reply has been deleted. Authored by the Zustelldienst.
-
-### Deprecated
-
-- Event `forward-submission` is now deprecated and [will be removed in a future release](https://git.fitko.de/fit-connect/planning/-/issues/310). [`(planning#1292)`](https://git.fitko.de/fit-connect/planning/-/issues/1292)
-
-
-## [1.1.0]
-
-### Changed
-
- - `$schema` von einem Enum in eine RegEx geändert [`(planning#608)`](https://git.fitko.de/fit-connect/planning/-/issues/608)
-
-## [1.0.0]