Documentation for the samples

[hame-c8y]

At the moment the only documentation for the samples here:
https://github.com/Cumulocity-IoT/cumulocity-python-api/tree/main/samples

is the name of the Python file and the inline comments.

It would be good to either have Markdown file in the samples directory giving a brief summary of each sample or to have a comment block at the beginning of each sample explaining the sample as a whole.