Generate cross-language documentation for settings

[ok-nick]

It's difficult to properly document settings in a way that is accessible to all languages. I propose that we leverage the work in #1447 to add JSON schemas to all our settings and auto-generate documentation via jsonschema2md. We can use the markdown to render it on our website.

The same concept can also be applied to our other structs such as for manifest definitions, assertions, reports, etc.

[crandmck]

Yes, this is a good idea and would replace the temporary solution I cobbled together to produce docs for Settings, ManifestDefinition, and Reader using the JSON schema; cf. https://github.com/contentauth/json-manifest-reference.

Ideally, the doc should be regenerated for each release (i.e. via GH workflow) and as you say get integrated into the docs similarly to https://opensource.contentauthenticity.org/docs/manifest/json-ref/manifest-def and https://opensource.contentauthenticity.org/docs/manifest/json-ref/reader. (I didn't yet add Settings since it was still evolving.)

Also, I don't think we want to generate the md files in this repo. We should do something similar to what we did in the Python repo in contentauth/c2pa-python#164.

[ok-nick]

@crandmck That's perfect! When I get around to it I can look into possibly setting up a workflow that sends a PR to that repo with the new schemas. It looks like we have the documentation generation part all figured out.