Update chart release process

[jessebot]

Is your feature request related to a problem? Please describe.

Howdy! I'm just getting started assessing the state of this repo for use with openbao, so expect more Issues and PRs :)

Right now the chart is available directly via the repo, but the docs in the README still say to use hashicorp's hosted helm repo.

Describe the solution you'd like

I can setup some GitHub actions to release this chart each push to main and update the README with current installation info.

See a couple of examples of the release workflow I'd implement:
https://github.com/small-hack/bitwarden-eso-provider/blob/main/.github/workflows/cd-helm-release.yml
https://github.com/nextcloud/helm/blob/main/.github/workflows/release.yaml

Describe alternatives you've considered

Happy to have the release go somewhere else, but the standard github actions are generally enough.

Additional context

If we use the github workflow I suggest above, we'll need to enable github pages for this repo, and we'll also need to enable write content permissions for the github actions in this repo, which is accessible in the Setting menu of this repo.

Feel free to assign to me.

[jessebot]

Chart is now releasing as of https://github.com/openbao/openbao-helm/releases/tag/openbao-0.1.0 due to #2. Closing as completed.