Detailed function documentation

[ReinhardKeil]

We will use a doyxgen approach to create the sds function documentation.

ToDo a txt file with detailed information about each function and an example for each function group.

The following commands generate the *.md files from Doxygen that are included in MKDocs.

doxygen
npx moxygen -i ./documentation/doxygen/xml -o ./documentation/api

Note: on windows this requires nodejs that can be installed from https://nodejs.org