Windows package resolution fails due to DocC generated filenames

The DocC documentation files generated within this SwiftPM package contain filenames that are incompatible with Windows path restrictions, causing package resolution to fail for any SwiftPM package that declares a dependency on `apple/SwiftUsd`.

I don't think this package needs to change anything - the root cause lives upstream in `swiftlang/swift-docc`. I'm opening this primarily to raise awareness and to see if there's appetite here to lend weight to a fix on that side. I've added context on the incompatibility [here](https://github.com/swiftlang/swift-docc/pull/668#issuecomment-4824814598).

Start with the linked swiftlang/swift-docc pull request comment and reproduce package resolution on Windows for a package depending on apple/SwiftUsd. Confirm which generated DocC filenames violate Windows path restrictions; this issue is resolved when the upstream fix lands or the dependency no longer fails.

Written by the indexing model from the issue text.