/changelog, rendered from the registered :changelog markdown file.
This used to be a shim that looked for GamendWeb.HostChangelogLive by name
and rendered "unavailable in standalone web mode" when it found nothing —
so every host wrote the page itself, and the two that did wrote it twice.
The page is GamendWeb.ContentPages.changelog/1 now; a host that wants
something else routes its own module, which the route macro already allows.