added cpu() virtualization, flags

docs/network.html

@@ -287,7 +287,7 @@ si.networkInterfaces().then(data => console.log(data));</code></pre class="examp
     type: 'wired',
     duplex: 'full',
     mtu: 16384,
-    speed: -1,
+    speed: null,
     dhcp: false,
     dnsSuffix: '',
     ieee8021xAuth: '',
@@ -496,8 +496,8 @@ setInterval(function() {
     tx_bytes: 180934681,
     tx_dropped: 0,
     tx_errors: 0,
-    rx_sec: -1,
-    tx_sec: -1,
+    rx_sec: null,
+    tx_sec: null,
     ms: 0
   }
 ]
@@ -810,4 +810,4 @@ setInterval(function() {
   </script>
 </body>
 
-</html>
+</html>