docs(errors): remove confusing good-to-know since global-errors.tsx also show in dev as of 15.2 (#76825)
## Why?
The "Good to know" has a typo, and it is probably better not mentioned. The https://nextjs.org/docs/app/building-your-application/routing/error-handling#handling-global-errors page does not mention (the fact that `global-errors.tsx` now show in `next dev`) it either.