kube-prometheus: Move service monitors to target folder

With 1d00e0ab ("ServiceMonitor: Enable Prometheus to select ServMon
outside own ns") merged: To emphasize the fact, that ServiceMonitors can
be deployed alongside their targets, this patch moves the Alertmanager,
Kube-State-Metrics, Node-Exporter and Prometheus Operator
Service-Monitor into the respective target folder in the kube-prometheus
project.

manifests/node-exporter/node-exporter-service-monitor.yaml

@@ -0,0 +1,22 @@
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  labels:
+    k8s-app: node-exporter
+  name: node-exporter
+  namespace: monitoring
+spec:
+  endpoints:
+  - bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
+    interval: 30s
+    port: https
+    scheme: https
+    tlsConfig:
+      insecureSkipVerify: true
+  jobLabel: k8s-app
+  namespaceSelector:
+    matchNames:
+    - monitoring
+  selector:
+    matchLabels:
+      k8s-app: node-exporter