I've just read the release notes for External API and the documentation for the activity and was wondering whether the documentation for the REST API documentation will be updated with the new entrypoints and examples?
Not sure it will be in API documentation as it's a data management activity.
here are links for a tutorial and doumentation on this new feature. Keep in mind that it's public beta.
External API Activity (beta)
As mentioned I had already read that but I am missing something about it in this document:
Adobe Campaign Standard API https://docs.campaign.adobe.com/doc/standard/en/api/ACS_API.html