-----
* **Improvement** - ``content_type`` and ``field`` are moved into ``ProceedingMeta`` model from ``Transition`` model. This requires to migrate ``0002``. This migrations will move value of the fields from ``Transition`` to ``ProceedingMeta``.
* **Improvement** - Slug field is added in ``State``. It is unique field to describe state. This requires to migrate ``0002``. This migration will set the field as slug version of ``label`` field value. (Re Opened -> re-opened)
* **Improvement** - ``State`` model now has ``natural_key`` as ``slug`` field.
* **Improvement** - ``Transition`` model now has ``natural_key`` as (``source_state_slug`` , ``destination_state_slug``) fields
* **Improvement** - ``ProceedingMeta`` model now has ``natural_key`` as (``content_type``, ``field``, ``transition``, ``order``) fields
* **Improvement** - Changelog is added into documentation.