Support versioning

It would be great if there was an option to show the version of the docs at the last tag by default.

This would solve an issue that has come up multiple times for users of Melos, where the docs are updated as part of a PR, but it takes some time before a new release is published. During that time, the docs are not fully in sync with the last version and that confuses users. For the Melos repo, we would need to be able to specify a prefix to match only the tags for the `melos` package releases, e.g. `melos-v`.

As a bonus, but not as important, there could be a menu that allows users to switch between the docs for different versions.