I've revisited the @Available directive because i realized it was not a huge change to allow for arbitrary "platforms" in the directive. That patch is now up here: allow arbitrary platform strings in the `@Available` directive by QuietMisdreavus · Pull Request #463 · apple/swift-docc · GitHub
With this change, these directives would now become legal, and these names will be printed verbatim on the documentation page:
@Metadata {
@Available(MyDependency, introduced: "1.0")
@Available("My Package", introduced: "2.0")
}