add example for k8s cronjob automated task example

[jkone27]

https://kubernetes.io/docs/tasks/job/automated-tasks-with-cron-jobs/

how does this translate in estafette, in particular, a cron job might be a "sidecar" of an app.. i didn't understand how i can set a container image (other thant the estafette extension image), so the two arrows above

apiVersion: batch/v1
kind: CronJob
metadata:
  name: hello
spec:
  schedule: "* * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: hello
            image: busybox:1.28 ##<<<<<<<<< i want to be able to set whatever image to invoke a custom command
            imagePullPolicy: IfNotPresent
            command: #<<<<<<< i want to set a custom command running from that image
            - /bin/sh
            - -c
            - date; echo Hello from the Kubernetes cluster
          restartPolicy: OnFailure

[jkone27]

i think image and command could be exposed for cronjob type, also maybe another action like deploy-multistage, to have separate manual trigger on stages.

deploy-multistage:
    stagename: first-stage
    
deploy-multistage:
   stagename: second-stage

as now multistage is bound to a single "deployment transaction / activity"