No documentation on config

```
import Trix from "trix"

document.addEventListener("trix-before-initialize", () => {
// Change Trix.config if you need
})
```

I failed to find any information on what config options it has. Is there a place where I can find the documentation on what options it has (and the possible values)?

Update:

Ok, I've found it in Wiki. But it would be good to add a note to Readme file that the configurations options are described in the Wiki because not everyone naturally looks to the Wiki (most projects don't have Wiki, so I expect to find an information like that in Readme).

Start with the README and the Trix configuration section in the project Wiki. Confirm where the available configuration options are documented, then add a README note pointing readers there; done means newcomers can find the configuration reference from the README.

Written by the indexing model from the issue text.