docs: Fix default value for `formatter` setting (#11560)

This PR fixes the default value for the `formatter` setting listed in
the docs.

The default value is `"auto"`:
https://github.com/zed-industries/zed/blob/194c43b84b4c2b0f2e78d8ef533bb99b6916f38c/assets/settings/default.json#L367

Resolves #11468.

Release Notes:

- N/A
5c2ec1705dMarshall Bowers committed on 5/8/2024, 2:42:41 PM· committed by GitHubparent2671b9c
1 file changedLine totals unavailable