[openbooks] New Chart

[Kab1r]

Description of the change

Add new chart for OpenBooks

Benefits

• Easier deployment of OpenBooks to any cluster
• Use existing k8s@home addons with OpenBooks

Possible drawbacks

Upstream does not use semver for docker images

Applicable issues

None

Additional information

Checklist

• [X] Title of the PR starts with chart name (e.g. [home-assistant])
• [X] Chart version bumped in Chart.yaml according to semver.
• [X] Chart artifacthub.io/changes changelog annotation has been updated in Chart.yaml. See Artifact Hub documentation for more info.
• [X] Variables have been documented in the values.yaml file.