Create a doc which compares Reloader vs. ConfigmapController about reloader

[faizanahmad055]

PR for this issue is here

[loknathsingh]

I have created a config map and configure that in deployment file. and when i make some changes in configmap .that changes don't reflect in Running Pod.
deployment:--
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
annotations:
configmap.reloader.stakater.com/reload: "nginx-configmap"
spec:
selector:
matchLabels:
app: nginx
replicas: 3 # tells deployment to run 2 pods matching the template
template: # create pods using pod definition in this template
metadata:
# unlike pod-nginx.yaml, the name is not included in the meta data as a unique name is
# generated from the deployment name
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
volumeMounts:
- name: nginx-config1
mountPath: /etc/nginx/conf.d/default.conf
subPath: default.conf
volumes:
- name: nginx-config1
configMap:
name: nginx-configmap
Config Map:---
apiVersion: v1
data:
default.conf: |2

   upstream backend {
        server 172.27.15.8:8081;
     server 192.0.0.1 backup;
    }
server {
    location / {
        proxy_pass http://backend;
    }
}

kind: ConfigMap
metadata:
creationTimestamp: 2019-01-18T05:33:31Z
name: nginx-configmap
namespace: default
resourceVersion: "9436168"
selfLink: /api/v1/namespaces/default/configmaps/nginx-configmap
uid: 971e503d-1ae2-11e9-9773-a08cfdc9b1ab