doc(production): replace ksonnet with Tanka (#1039)
doc(production): replace ksonnet with Tanka (#1039)

As `ksonnet` is long deprecated and [Tanka](https://github.com/grafana/tanka) being mature enough to replace it, we should show users how to do so.
grafana/loki,grafana/loki,grafana/loki,grafana/loki,grafana/loki,grafana/loki