Auto merge of #2203 - arcalinea:2142_security_log_message, r=daira

Add message directing users to security guide

Addresses #2142, which was blocking on updates to zcash/support/security.html. That page has now been added, so this message directing users to the site can be included.

It displays in the zcash-cli --help and --version message text, and on the zcashd metrics screen.

src/metrics.cpp

@@ -393,6 +393,9 @@ void ThreadShowMetricsScreen()
         // Thank you text
         std::cout << _("Thank you for running a Zcash node!") << std::endl;
         std::cout << _("You're helping to strengthen the network and contributing to a social good :)") << std::endl;
+
+        // Privacy notice text
+        std::cout << PrivacyInfo();
         std::cout << std::endl;
     }