Add manifests to deploy+monitor example app

manifests/examples/example-app/example-app-dev-depl.yaml

+kind: Service
+apiVersion: "v1"
+metadata: 
+  name: example-app
+  namespace: development
+  labels:
+    tier: frontend
+    team: frontend
+  annotations:
+    prometheus.io/scrape: 'true'
+spec: 
+  selector: 
+    app: example-app
+  ports:
+  - name: web
+    protocol: TCP
+    port: 8080
+    targetPort: web
+---
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: example-app
+  namespace: development
+spec:
+  replicas: 3
+  template:
+    metadata:
+      labels:
+        app: example-app
+        version: 1.2.0
+    spec:
+      containers:
+      - name: example-app 
+        image: quay.io/fabxc/prometheus_demo_service
+        ports:
+        - name: web
+          containerPort: 8080
+          protocol: TCP

manifests/examples/example-app/example-app-prod-depl.yaml

+kind: Service
+apiVersion: "v1"
+metadata: 
+  name: example-app
+  namespace: production
+  labels:
+    tier: frontend
+    team: frontend
+  annotations:
+    prometheus.io/scrape: 'true'
+spec: 
+  selector: 
+    app: example-app 
+  ports:
+  - name: web
+    protocol: TCP
+    port: 8080
+    targetPort: web
+---
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: example-app
+  namespace: production
+spec:
+  replicas: 5
+  template:
+    metadata:
+      labels:
+        app: example-app
+        version: 1.1.3
+    spec:
+      containers:
+      - name: example-app 
+        image: quay.io/fabxc/prometheus_demo_service
+        ports:
+        - name: web
+          containerPort: 8080
+          protocol: TCP

manifests/examples/example-app/prometheus-frontend-svc.yaml

+apiVersion: v1
+kind: Service
+metadata:
+  name: prometheus-frontend
+spec:
+  type: NodePort
+  ports:
+  - name: web
+    nodePort: 30100
+    port: 9090
+    protocol: TCP
+    targetPort: web
+  selector:
+    prometheus.coreos.com: prometheus-frontend

manifests/examples/example-app/prometheus-frontend.yaml

+apiVersion: prometheus.coreos.com/v1alpha1
+kind: Prometheus
+metadata:
+  name: prometheus-frontend
+  labels:
+    prometheus: frontend
+spec:
+  serviceMonitors:
+  - selector:
+      matchLabels:
+        team: frontend
\ No newline at end of file

manifests/examples/example-app/servicemonitor-frontend.yaml

+apiVersion: prometheus.coreos.com/v1alpha1
+kind: ServiceMonitor
+metadata:
+  name: frontend
+  labels:
+    team: frontend
+spec:
+  selector:
+    matchLabels:
+      team: frontend
+  scrapeInterval: 10s
+  endpoints:
+  - port: web
\ No newline at end of file