Update changelog

CHANGELOG.rst

@@ -9,12 +9,31 @@ and this project adheres to `Semantic Versioning`_.
 Unreleased
 ----------
 
+Upgrade notice
+~~~~~~~~~~~~~~
+
+If you're updating from 3.x, there is a migration path to use.
+Therefore, please install ``AlekSIS-App-Lesrooster`` which now
+includes parts of the legacy Chronos and the migration path.
+
 Added
 ~~~~~
 
 * New timetable interface based on calendar system.
+* Dialog for fast changing lessons and creating substitutions in the calendar. 
 * [Dev] LessonEvent and SupervisionEvent basing on calendar system.
 
+Changed
+~~~~~~~
+
+* Substitution PDF was updated to new timetable interface and 
+  therefore has a slightly different look.
+
+Removed
+~~~~~~~
+
+* Legacy timetable frontend.
+
 `3.0.2`_ - 2023-09-10
 ---------------------