Cargo currently warns when checking examples for both `oxc_formatter` and `oxc_formatter_json` because each crate has an implicit `formatter` example target. That makes both packages try to write `target/debug/examples/formatter`.
This renames the JSON formatter example to `json_formatter` and updates the usage comments in the example so the command stays accurate.
Checked with:
```sh
cargo check --examples -p oxc_formatter -p oxc_formatter_json
```