Remarks on modules development documentation

[c8y3]

These are remarks about documentation page Modules:

• attribute _module_description is not documented, but present of the code of existing modules
• could you please document the list of all possible parameters types that can be used in module configuration? From existing modules, I have collected bool, float, string, sensitive_string, textfield_json and textfield_html. But maybe there are more?

Thank you.