We have a change log, but it's for GSX only, and is already full of stuff, so we don't include it in the Release notes of the installer.
As with any MSFS scenery, the manifest.json at the root of the package contains the latest changes, which is shown when the scenery is on the Marketplace and you press the Info icon in the Content Manager.
However, for some reason, the Info are missing if the scenery is in the Community folder, this might possibly be a bug, since the package is the same as the one that gets submitted by Microsoft, no reason not to show the manifest in both cases. In fact, it HAS been reported as a bug on Asobo developers forum:
https://devsupport.flightsimulator.com/questions/15697/no-more-info-for-community-packages.html
