docs(alpine): quote release label value (#4460)

Labels should be quoted so that values such as "true" or "1" are not
interpolated to the wrong type.

docs/examples/alpine/templates/alpine-pod.yaml

@@ -9,7 +9,7 @@ metadata:
     app.kubernetes.io/managed-by: {{ .Release.Service }}
     # The "app.kubernetes.io/instance" convention makes it easy to tie a release to all of the
     # Kubernetes resources that were created as part of that release.
-    app.kubernetes.io/instance: {{ .Release.Name }}
+    release: {{ .Release.Name | quote }}
     # This makes it easy to audit chart usage.
     helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
     app.kubernetes.io/name: {{ template "alpine.name" . }}