[Feature Request]: Set the current docs branch to a tag instead of a branch name

### Prerequisites

- [x] I have searched existing issues to ensure this feature hasn't already been requested
- [x] I have tested using the latest version of docs-builder

### What problem are you trying to solve?

We currently have the option of setting a different publication branch per assembled repo. @SergeyKleyman suggested that we could instead use tags based on the current version in `versions.yml` as an option. That would ensure that the docs from the latest release are served instead of main's.

### Proposed Solution

In a snippet like this:

```
ecs:
current: 9.1 # releases do not always align with the Stack version
next: main
```

9.1 could be either the branch of the tag.

### Examples and Research

_No response_

### Alternative Solutions

_No response_

### Additional Context

_No response_

### How important is this feature to you?

Nice to have