witness-0.6.1: changelog.md

## [0.6.1] - 2022-09-12
- new ListLength type family and associated functions
- new Greater type family and associated functions
- new FixedList type indexed by PeanoNat
- new ListElement functions
- new OrderedWitnessMapFor and OrderedWitnessMapOf types
- new functions:
  - someForToSome

## [0.6] - 2022-05-08
- reorganise modules
- rename types and functions
- additional functionality

## [0.5] - 2020-09-22