Syncing config and experimental-features docs

### Checklist

- [X] My issue is specific & actionable.
- [X] I am not suggesting a protocol enhancement.
- [X] I have searched on the [issue tracker](https://github.com/ipfs/kubo/issues?q=is%3Aissue) for my issue.

### Description

We currently have [config.md](https://github.com/ipfs/kubo/blob/master/docs/config.md) and [experimental-features.md] https://github.com/ipfs/kubo/blob/master/docs/experimental-features.md. However, not all of the experimental features that are configurable from the config file are listed in config.md, and some of the experimental options in config.md are not listed in experimental-features.md.

This makes discovery of experimental feature more painful than it needs to be and users end up needing to check both places.

https://github.com/ipfs/kubo/pull/9181 was a bandaid to make this more reasonable, but these documents should be refactored to be consistent.