add external docker registry kubernetes code example

Example 1: how to login to docker inside kubernetes cluster

kubectl create secret docker-registry regcred --docker-server=<your-registry-server> --docker-username=<your-name> --docker-password=<your-pword> --docker-email=<your-email>

Example 2: how to expose external ip in kubernetes

kubectl expose deployment hello-world --type=LoadBalancer --name=my-service