Index of Releases in Bucket

I'm trying to write a plugin for the [asdf](https://github.com/asdf-community/) [mise](https://mise.jdx.dev/) [vfox](https://vfox.lhan.me/) collection of tools (vfox in this case), and rather than parse the s3 bucket for nightly release information, I was wondering if you could leave an index in the bucket, or allow me to do a PR that would do that.

No files, tests, or entry points are identified in the issue. Start by examining the S3 bucket's current nightly release layout and the needs of asdf, mise, and vfox plugins; done would mean a documented, usable release index is available without parsing the bucket contents.

Written by the indexing model from the issue text.