Persistent OS Configurations for Quick Start

General MR

Summary

• This merge request includes modifications to Step 4 in the Quick Start Guide. The commands in this step were modified to configure the operating system parameters to be persistent after a restart of the server. The commands used previously would be reset to their default value which would cause some pods to not be able to deploy after a version change or update of Big Bang.
• A notice was added for users that modify the CoreDNS pod that changes will not persist after a restart of the server as well. The provided solution was to re-apply the configuration. This solution was chosen to maintain simplicity of the Quick Start Guide instead of adding additional steps to deploy a new CoreDNS pod.