The short answer is, that you can't.
Many changes don't even get a forum posting. Maybe they end up as a comment inside another thread. You have to wade through each and every change in the project change log and figure out yourself if it applies to mission planner, arduplane, copter , rover or whatever else.
That's not quite right.
The Mission Planner itself is updated almost daily, so we can't post on that every time. But you can follow them with the Michael Oborne updates in the changelogs
so, If I am now at ArduPlane 2.28 - and latest tag I can filter by is 2.27alpha , .. how do I limit my reading to what's important ?
If I knew the data 2.28 got released, - then I could read all changes since then ?
Thank you. - will try to detect changes on page until a RSS feed is available :)