For example, `plasma-welcome --after-upgrade-to 5.25.0` could display a page with some friendly text and a link to https://kde.org/announcements/plasma/5/5.25.0.
Done in https://invent.kde.org/ngraham/welcome-app/-/commit/af832a952fd904c2ee1fe05ff52c871aee778f2d! The invocation is `plasma-welcome --after-upgrade-to 5.25` (it adds the trailing zero automatically