ToDo's towards a usable library

[prisae]

These are the principal ToDo's to get to a usable state. Additional "ToDo's" are tracked in #2, #3, and #4.

• Write Digital Linear Filters section, with references to most important articles.
• Write What is libdlf.
• Add code examples of its usage.
• Add CI test to validate json file. Add simple json test; improve python package #12
• Add CI tests for all filters.
• Add automatic Zenodo and badge. 528aa3b

[kerrykey]

We might think about a Recommended Applications section where we could document application experiences with the filters. I know I've found modeling applications where one filter is great and another not so good, and then other modeling scenarios where the opposite is true.

[prisae]

Sounds great @kerrykey , feel free to start such a section. Not sure if moving to a more dedicated documentation (Sphinx or another tool) might be better at some point (also for nicer maths etc). But I feel that for the moment the simple README is OK.

[prisae]

I added a simple test for all filters to the Python-GHA (.github/workflows/linux_python.yml). That should be enough. We should test new filters visually for a more extensive model, but that has only to be done ONCE, when adding a filter.