Mention pf guide to 'vpn only' mode. close #35.
Mention pf guide to 'vpn only' mode. close #35.

ScheerMT/OS-X-Yosemite-Security-and-Privacy-Guide,DeadLion/macOS-Security-and-Privacy-Guide,drduh/OS-X-Yosemite-Security-and-Privacy-Guide,drduh/macOS-Security-and-Privacy-Guide,drduh/OS-X-Security-and-Privacy-Guide