Add Helm chart publishing Github action and instructions on how to configure a naive Helm chart

For services that are going to be published as containers, we may also want to configure a github action to validate, lint, version and publish the Helm chart, with best practices and standards.

Note that I think the creation of the Helm chart should be left to `helm create`

Start by reviewing how this template represents GitHub Actions and service configuration, then use `helm create` as the reference for the naive chart setup. Define the validation, linting, versioning, and publishing workflow plus configuration instructions; done means the action and documented setup support a containerized service chart.

索引モデルが issue の本文から書いたものです。