I can read docs about...
- the newly introduced Historic Task resource
- Add new entry to resource table  and check read column
- permissions by resource "Historic Instance Permissions"
- mention that they are taken into account by history cleanup
- mention, that they need to be configured explicitly
- new "Default Read Variable Permissions"
- What does "(for standalone tasks)" mean? Follow-up ticket
- Add "In case of Historic Tasks: Read Variable"
- the process engine configuration flag enableHistoricInstancePermissions
- limitations with the legacy cleanup mechanism (end-time-based strategy)