It’s the #announcements, for what would there be announcement on Manjaro’s forums? About Manjaro, obviously. And once there, you can see it’s about [Stable update]s, [Testing updates]s, [Unstable update]s, or [Stable-staging update]s.
Just do a bit more reading than (badly) skimming the surface. There is a lot of other info there as well, that you’ll be thankful you didn’t miss.
Yeah, I had to learn that myself, so yes, I’m talking from experience.
Edit:
Also, there are fairly regularly update announcements in the forum, as the section would suggest. When those announcements are released, they are the top busiest forum topic.
There are also RSS feeds for the announcements, as well as the matray tray app for it. So I think it’s well covered. If you don’t expect to be spoon-fed, that is.