This notification setting:

sounds like it might include whenever the rich text field is edited, but this doesn’t seem to be the case. This would be nice to include in the notification settings, perhaps with the option between in-app and email. The nature of the notification itself is not as important. It could be based off of the history of the rich text field itself (e.g. a notification per “snapshot”), or it could be a daily digest. Just something that makes people aware that changes have been made to the rich text field.
This is especially relevant for our documents/internal wiki.