Add a recommendation on how to import act (#526)

closes #524

Author: just-boris

docs/react-testing-library/api.md

@@ -290,4 +290,4 @@ errors in your tests).
 This is a light wrapper around the
 [`react-dom/test-utils` `act` function](https://reactjs.org/docs/test-utils.html#act).
 All it does is forward all arguments to the act function if your version of
-react supports `act`.
+react supports `act`. It is recommended to use the import from `@testing-library/react` over `react-dom/test-utils` for consistency reasons.