Should be support branch for normal maintenance flow

[Thadir]

Currently, nomad-pack supports the following options:

  --ref=<string>
    Specific git ref of the registry or pack to be added. Supports tags,
    SHA, and the latest. If no ref is specified, it defaults to the latest. Running
    "nomad registry add" multiple times for the same ref is idempotent,
    however running "nomad-pack registry add" without specifying a
    ref, or when specifying @latest, is destructive, and will overwrite
    current @latest in the global cache. Using ref with a file path is not
    supported.

  --target=<string>
    A specific pack within the registry to be added.

But if your updating a template, you do not want to directly work on main but often in a branch. So adding the support for --branch or allow --ref to also try to go to the branches would be nice.

Example:
nomad-pack registry add community github.com/hashicorp/nomad-pack-community-registry --branch=feature/DEV-26331-add-templates