Registry documentation

[abstractionfactory]

We would like to have a user-readable registry documentation, detailing questions such as:

1. How do I add a provider to the registry?
2. Why isn't my provider getting indexed?
3. Why isn't my documentation indexed?

This would take the extent of multiple pages because we want to explain in detail how to publish a provider, module, etc. The frontend code is mostly in place, but we have questions to be resolved.

Questions:

• [ ] Do we publish this as part of the OpenTofu documentation or separately? (This is specific to the OpenTofu registry, not OpenTofu.)
• [ ] If we publish it separately, do we make the documentation available via the API, or is it part of the frontend?

[abstractionfactory]

Adding help wanted because we would like to see some use cases / feedback on how an API would be useful.