Specification for parse_kv_items and parse_kv_config

parse_kv_items and parse_kv_config was introduced by @drybjed and is now a core part of DebOps. People working with DebOps need a clear understanding of it. Documentation what the filters do are contained in the actual role documentation but are specific to the role then. This will require people writing new roles to actually look into the code to figure out what it does and how to use it in their own roles. As already proposed by @tasosalvas, specification of the filters is needed defining exactly what their behavior is. I went for a hands-on approach when the filters where introduced and wrote the unit tests to reverse and "document" what they do. I would still be interested in a design document about our direction.

And maybe a "Not invented here" approach, but no better alternative comes to mind for me currently to solve all of the things that the filters do.

https://github.com/debops/debops/blob/master/ansible/roles/ansible_plugins/filter_plugins/debops_filter_plugins.py

I just want to track this here. Again, no pressure. I know maintaining a project is hard and this is a FOSS project. My idea is more that people interested in DebOps maybe can reverse the filters as well and not write unit tests this time but think about the problem and come up with a design document.