How to: CRD example "resourcedefinition.yaml"
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: crontabs.stable.example.com # must match `
.
` spec fields below
spec:
  group: stable.example.com # REST API: /apis/
/
versions: # list of supported versions
    - name: v1
      served: true # enabled/disabled this version, controls deprecations
      storage: true # one and only one version must be storage version.
      schema:
        openAPIV3Schema:
          type: object
          properties:
            spec:
              type: object
              properties:
                cronSpec:
                  type: string
                image:
                  type: string
                replicas:
                  type: integer
  scope: Namespaced # or Cluster
  names:
    plural: crontabs # REST API: /apis/
/
/
singular: crontab # used for display and as alias on CLI
    kind: CronTab # CamelCased singular type for resource manifests.
    shortNames:
    - ct # allow `crontab|ct` to match this resource on CLI
```