Automagically create documentation from Python docstrings

[rzbrk]

At the moment, the documentation in the README file is created manually in parallel to inline documentation (Python docstrings). This will be avoided by generating the documentation from the inline documentation.

I choose PyDoc because it is very easy to operate and provides enough features for this small software project.

ToDos:

• [x] Migrate documentation from README to source code files if necessary
• [x] Test generation of documentation with PyDoc
• [x] Adapt structure of documentation because not all documentation is generated from inline documentation
• [ ] Document the documentation approach

[rzbrk]

All documentation from old README was moved to inline docstrings. Folder docs for project documentation was established. Source code docu was generated with pydoc. However, HTML output was not used because it cannot be properly displayed online on Github. Instead, the plain text output of pydoc was used.

Open:

• [ ] Autogenerate docu with Github Actions when pushing new code to Github repo?
• [ ] Display "beautiful docu" using Github pages?