Add nupkg download links (if they exist in JSON) for Windows

[theopolis]

This is a reminder to add a new link on the downloads page for Windows nupkgs. These should be generated by CMake in the future, they are built manually now by @muffins.

[mike-myers-tob]

Update: I believe these are now generated automatically, since I've seen them in the build artifacts of every GitHub Actions flow.

But we have yet to add links to them to the site's downloads page.