<CodeGroup dropdown> uses a YAML icon for TOML

[adtac]

minimal repro:

<CodeGroup dropdown>
```json foo.json
{"foo": "bar"}
```

```toml foo.toml
foo = "bar"
```
</CodeGroup>

here's an example docs page for live repro: https://subtrace.dev/docs/cloudflare (see the wrangler.json / wrangler.toml)

example screenshot:

[atharvamhaske]

hey would like to work on this smol issue :)