Fix for khcheck-storage template

[blame19]

This addresses #895

Many of the variables referenced inside khcheck-storage failed with the following error:

Error: template: kuberhealthy/templates/khcheck-storage.yaml:24:23: executing "kuberhealthy/templates/khcheck-storage.yaml" at <.Values.check.storage.image.registry>: can't evaluate field Values in type interface {}

Error: template: kuberhealthy/templates/khcheck-storage.yaml:44:25: executing "kuberhealthy/templates/khcheck-storage.yaml" at <.Values.check.storage.resources.requests.cpu>: can't evaluate field Values in type interface {}

this due to helm not being able to render the variables correctly inside the given {{ range }}. The $ notation fixes this (ref: https://helm.sh/docs/chart_template_guide/variables/)

I was able to test this in my local env with the default values.yaml, except with the addition of:

 # external check from registry
 # https://github.com/ChrisHirsch/kuberhealthy-storage-check
   **enabled: true**
   # empty string indicate default storage class
   # kubectl get storageclass
   # or put storage class names into list
   **storageClass: ["managed-premium"]**
   runInterval: 5m
   timeout: 10m
   image:
     registry: chrishirsch
     repository: kuberhealthy-storage-check
     tag: v0.0.1
   extraEnvs:
     CHECK_STORAGE_IMAGE: bitnami/nginx:1.19
     CHECK_STORAGE_INIT_IMAGE: bitnami/nginx:1.19
   nodeSelector: {}
   tolerations: []
   #- key: "key"
   #  operator: "Equal"
   #  value: "value"
   #  effect: "NoSchedule"
   resources:
     requests:
       cpu: 10m
       memory: 50Mi```

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[mikeinton]

I was able to reproduce this error and confirm the fix. Thanks @blame19 for addressing this.