Fix comments on how to enable/disable Hermes on iOS
Fix comments on how to enable/disable Hermes on iOS

Summary:
This comment on how to enable/disable Hermes went out of sync with the release of the New Architecture. Got reported on the website here: https://github.com/facebook/react-native-website/issues/3105
I'm fixing it.

Changelog:
[Internal] [Changed] - Fix comments on how to enable/disable Hermes on iOS

Reviewed By: cipolleschi

Differential Revision: D36204189

fbshipit-source-id: 5831a9500477115ebe5fa5cb62176ceefc722839

javache/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,janicduplessis/react-native,janicduplessis/react-native,facebook/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,javache/react-native,janicduplessis/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,javache/react-native,javache/react-native,facebook/react-native,javache/react-native,javache/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,facebook/react-native