Add dashboard warning message in openfaas chart notes

Signed-off-by: Han Verstraete (OpenFaaS Ltd) <[email protected]>

Author: welteki

chart/openfaas/templates/NOTES.txt

@@ -8,3 +8,9 @@ To retrieve the admin password, run:
 
   echo $(kubectl -n {{ .Release.Namespace }} get secret basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode)
 {{- end }}
+
+{{- if and .Values.dashboard.enabled (not .Values.dashboard.signingKeySecret) }}
+
+Warning: The dashboard is using auto generated signing keys.
+These should only be used for development. See: https://docs.openfaas.com/openfaas-pro/dashboard/
+{{- end}}