Helm improvements: default values, schema validation, etc.

[kondratyevd]

• Example values.yaml file to serve as a starting point for future implementations
• JSON schema to validate values.yaml and throw meaningful errors
• Separate directory for existing values files
• GitHub Action workflow to validate values files against JSON schema
• Check if any Helm templates need default values to be specified or fixed
• Automate documentation or otherwise synchronize with the schema
• Embed auto-generated documentation into sphinx website

[kondratyevd]

Instructions to generate a JSON schema from values.yaml: https://www.arthurkoziel.com/validate-helm-chart-values-with-json-schemas/