Fix comment referencing the folded in react hook testing library

[jasikpark]

The react hooks testing library package was folded into the main package, the instructions should reflect this

Feel free to change the wording of the comment, I just added it as a base example, I'm sure you can think of something more specific / better in flow with the surrounding text

[kentcdodds]

This has been "merged". Thanks!

[kentcdodds]

@all-contributors please add @jasikpark for docs

[allcontributors[bot]]

@kentcdodds

I've put up a pull request to add @jasikpark! :tada: