As we would have added the type-safe helm values API (OSSM-4050), we have to add description field for each value into the Istio CustomResourceDefinition.

Acceptance Criteria:

• a description field should contain the chart head comments of this specific field
  • E.g. for the base.validationURL, here is the field related description https://github.com/maistra/istio/blob/maistra-3.0/manifests/charts/base/values.yaml#L8-L9