[feat] Add prompt about master needing internet access

When package updates go through the master node, that master needs internet access.
Therefore, prompt the user about this requirement.

Resolves #146

setup/so-whiptail

@@ -1027,7 +1027,17 @@ whiptail_master_updates() {
 			;;
 	esac
 
+}
 
+whiptail_master_updates_warning() {
+	[ -n "$TESTING" ] && return
+
+	whiptail --title "Security Onion Setup"\
+	--msgbox "Updating through the master node requires the master to have internet access, press ENTER to continue"\
+	8 75
+
+	local exitstatus=$?
+	whiptail_check_exitstatus $exitstatus
 }
 
 whiptail_node_updates() {