Add JSON schema for values.yaml.

[bear454]

... including two small consistency fixes for the values file.

Having a JSON schema allows for helm lint to validate the supplied values, both in values.yaml and via --set command line arguments.

JSON schema is set to version draft/2019-09, the newest version supported by AWS EKS Add-ons.

While there is still some work that could be done for validation, IMO this schema can be considered functionally complete:

• all non-deprecated attributes are included;
• types are defined as observable, including nulls as referenced in the standard values or descriptions;
• all descriptions from the README are included;
• formats, enumerations, and regex patterns are defined based on kubernetes and OpenShift requirements;
• fixed attributes are set via regex pattern validation (e.g. Azure "DONOTMODIFY" attributes);
• and of course helm lint shows 0 failures.

Additional validations are welcomed!