Check documentation for default fields

[pi-sigma]

The documentation for config variables corresponding to default model fields should be checked at some point. For example, the documentation for JSONField says the expected value is of the form 'some_key': 'Some value'}. This is not false, but there could be other values (int, list, None).

Can be taken up in the context of adding support for YAML config files or when corrections to the generate_docs functionality become necessary.

Additional things:

• Add remark to documentation template (visible to the end user) that the docs are auto-generated
• Add comment to documentation template (only visible to devs) that the docs should not be edited manually (to prevent "corrections" of spelling errors, stylistic errors etc., which need to be fixed elsewhere, e.g. on the models from which the documentation is pulled)