docs(): adding additions details to readme

Signed-off-by: gkarthiks <github.gkarthiks@gmail.com>

README.md

@@ -4,11 +4,31 @@
 ![License](https://img.shields.io/github/license/gkarthiks/container-resource-exporter.svg)
 ![Release](https://img.shields.io/github/tag-date/gkarthiks/container-resource-exporter.svg?color=Orange&label=Latest%20Release)
 
-Container Resource Exporter (CRE) is a simple metrics expoerter which will export the following data in the [Prometheus](https://prometheus.io/) format. This can be utilized to trigger a pro-active alert from the the [Prometheus Alert Manager](https://prometheus.io/docs/alerting/alertmanager).
+Container Resource Exporter (CRE) is a metrics expoerter which will provide the *container* resource `request/limit/usage` metrics data on realtime in the [Prometheus](https://prometheus.io/) format. This can be utilized to trigger a pro-active alert from the the [Prometheus Alert Manager](https://prometheus.io/docs/alerting/alertmanager).
 
-### Sample CRE metrics exported:
 
+## Cluster Level:
+By default the *CRE* will watch for the entire cluster, scrapes the resources for each and every container and exports them along with the total count of pods in each namesapces.
+
+To run in the *cluster mode*, the *CRE* will require a *service account* which has cluster level read access and `list` actions on the resource `pods` in `core v1` apiGroup and `metrics` apiGroup.
+
+
+## Contained Namespace:
+To run the *CRE* in a contained namespace, i.e., watch only particular namespace; add the following environment variable `WATCH_NAMESPACE`. This can be easily accompolished with the `downward api` in *Kuberneres* as shown below.
+
+```yaml
+- env:
+    - name: WATCH_NAMESPACE
+        valueFrom:
+        fieldRef:
+            fieldPath: metadata.namespace
 ```
+
+Still, *CRE* will require a *service account* which has access to `list` all the `pods` under `core v1` apiGroup and `metrics` apiGroup.
+
+### Sample CRE metrics exported:
+
+```prometheus
 # HELP cpu_limit CPU Limit by deployment
 # TYPE cpu_limit gauge
 cpu_limit{container_name="alertmanager",namespace="default",pod_name="prometheus-alertmanager-74bd9d5867-gmlj9",status="Running "} 1
@@ -45,3 +65,16 @@ total_pod{namespace="default"} 1
 ```
 
 Effortlessly get the Resources' request, limit and current usage by containers in your cluster/namespace.
+
+## Sample Grafana dashboard visualization
+The below sample [Grafana](https://grafana.com/) dashboard will show the sample metrics record for 
+- Total pods in the namespace over the time
+- Total CPU Limit/Request/Usage in the namespace
+- Total Memory Limit/Request/Usage in the namespace
+- A sample pod's CPU Utilization
+- A sample pod's Memory Utilization
+
+![alt](./grafana-dashboard.jpeg)
+
+## Docker Image:
+The docker image ofcan be found [here <img src="./docker-logo.png" width="40" height="40" align="center"/> .](https://cloud.docker.com/repository/docker/gkarthics/container-resource-exporter)