The version described by the application's release notes.
The release notes version is displayed on the What's New page, above the release notes.
If not set, [property@AboutWindow:version] will be used instead.
For example, an application with the current version 2.0.2 might want to keep the release notes from 2.0.0, and set the release notes version accordingly.
See [property@AboutWindow:release-notes].