Address comments

jsonnet/kube-prometheus/kube-prometheus.libsonnet

@@ -6,9 +6,14 @@ local k = import 'ksonnet/ksonnet.beta.3/k.libsonnet';
 (import 'alertmanager/alertmanager.libsonnet') +
 (import 'prometheus-operator/prometheus-operator.libsonnet') +
 (import 'prometheus/prometheus.libsonnet') +
-(import 'kubernetes-mixin/mixin.libsonnet') +
-{
+(import 'kubernetes-mixin/mixin.libsonnet') + {
+  kubePrometheus+:: {
+    namespace: k.core.v1.namespace.new($._config.namespace),
+  },
+} + {
   _config+:: {
+    namespace: 'default',
+
     kubeStateMetricsSelector: 'job="kube-state-metrics"',
     cadvisorSelector: 'job="kubelet"',
     nodeExporterSelector: 'job="node-exporter"',