Minor clarification on test setting

### Where should the content be changed?

https://conda-forge.org/docs/maintainer/conda_forge_yml.html#test

### What should be changed?

The doc states that default is "all" but it is not clear what this means as two setting options are listed. I assume all == native_and_emulated but looking at the code it is not apparent that this is the case?

>
> This is used to configure on which platforms a recipe is tested. Default is all.
>
> test: native_and_emulated
>
> Will do testing only if the platform is native or if there is an emulator.
>
> test: native
>
> Will do testing only if the platform is native.

### Additional information

_No response_

### Incorrect or outdated

- [X] Incorrect
- [ ] Outdated