A new category named Draft visible only to member of the group draft-writer was created.
It allows to leverage the shared draft feature of Discourse and is used to draft posts before publicly releasing them. (e.g Release Announcement)
security settings of draft category
shared draft category settings
The draft category was then set as shared draft category in the settings.
For more details, see Shared Drafts: Allow staff to collaborate on posts before publishing - announcements - Discourse Meta,