Add class/instance and module attributes/properties documentation

[leandro-lucarella-frequenz]

What's needed?

We need to properly document class/instance and module attributes/properties documentation so they appear in the generated docs.

Proposed solution

For now how to best do this is documented in this issue:

• Use MkDocs to build the documentation #25

Use cases

No response

Alternatives and workarounds

No response

Additional context

No response