Protocol notes don't actually deploy multiple versions

[hdevalence]

#5 changes the protocol notes so that there's a version field included in the URL paths. This way, in the future, there can be a separately-rendered set of docs for each tag or branch.

However, the current deploy pipeline uses the firebase cli, which only does atomic deployments, so there's no way to add a set of files to the existing site, and this means that only the most recently deployed version will actually appear. At the moment this isn't a big deal because there's just one version anyways.

[hdevalence]

A setup that would be really useful for development would be:

• on pushes to branch branch, deploy notes to protocol.penumbra.zone/branch/..., removing any previous contents of /branch/...;
• on pushes of tag tag, deploy notes to protocol.penumbra.zone/tag/..., removing any previous contents of /tag/...;
• when a branch branch is deleted, remove everything under protocol.penumbra.zone/branch/...;

This way, it would be possible to preview notes or API documentation of in-progress work.

I think this should be possible with Github Actions, but it might require changes to the hosting in order to be able to make partial updates and deletions, since the firebase cli only performs atomic updates. S3+Cloudfront or something would probably work just as well.

[hdevalence]

We haven't done this in the last year and a half and things have worked out, so we can probably skip it.