Added sudo shell note.

Author: uc-msft

samples/features/sql-big-data-cluster/deployment/kubeadm/README.md

@@ -50,6 +50,7 @@ To install docker, you can follow the steps below:
 
 ### Instructions
 
+1. Start a sudo shell context
 1. Execute [ubuntu/setup-k8s-prereqs.sh](ubuntu/setup-k8s-prereqs.sh/) script on each machine
 1. Execute [ubuntu/setup-k8s-master.sh](ubuntu/setup-k8s-master.sh/) script on the machine designated as Kubernetes master
 1. After successful initialization of the Kubernetes master, follow the kubeadm join commands output by the script on each agent machine