Update release workflow and docs

[ChenYi015]

Purpose of this PR

Update release workflow, the release steps are as follows:

1. Update VERSION file
2. Update version and appVersion in chart.yaml and make helm-docs
3. Commit the changes and create a PR to the release branch
4. After the PR is raised, a workflow in check-release.yaml will be triggered to do some check e.g. whether the version matches semver pattern, whether the chart version/appVersion matches this version and whether the version tag already exists
5. Once the PR is merged, a workflow in release.yaml will be triggered to build and publish docker images to Docker hub and create a draft release
6. Once the draft release is published, a workflow in release-helm-charts.yaml will be triggered to update Helm repo index file

Change Category

Indicate the type of change by marking the applicable boxes:

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

• Since a tag pushed by action workflow cannot trigger other workflows, we need to push the tag manually to trigger the release workflows.
• I have attempted to merge all the release-related workflows into one workflow file, but that requires more modifications to the workflow file, particularly because the current workflow for releasing Docker images functions well when it retrieves context from a tag push event.

Checklist

Before submitting your PR, please review the following:

• I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
• Existing unit tests pass locally with my changes.

Additional Notes

[ChenYi015]

/hold
/assign @vara-bonthu @andreyvelich

[vara-bonthu]

Thanks and the updated release workflow looks good to me. Approving this PR.
@andreyvelich add lgtm label once you are happy with your comments

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vara-bonthu

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[andreyvelich]

Do we need this, since we make the commit to the release branch via release GitHub action ?

[ChenYi015]

I think this is needed, for that the release GitHub action is used to create a new draft release, not to make a commit to the release branch. So we need to update chart version /appVersion and README at the same time when we modify the VERSION file.

[ChenYi015]

/hold cancel

[andreyvelich]

/lgtm