Broken link to retext-profanity rules

### Subject of the issue

The README says:
> See [retext-equality](https://github.com/retextjs/retext-equality/blob/main/rules.md) and [retext-profanities](https://github.com/retextjs/retext-profanities/blob/main/rules.md) for all rules.

In the retext-profanity repository, the file `rules.md` doesn't exist.