Setup an way to publish announcements
A changelog is great but you can't put everything into it, stuff like the move from
stable would have to be put into it.
I think a mailing-list would quite suck for this as there is often a lack of public archives and they often seriously lack accessibility/features, a blog and/or a planet of pleroma maintainers blogs (limited to a category/tag) would be better. Something like the in-between forum and mailing-list that is discourse could be considered but it probably quite heavy to host&maintain (we already have gitlab for the pain).