add help menu

menu.js

@@ -45,6 +45,20 @@ module.exports = function(win){
         {role: 'minimize'},
         {role: 'close'}
       ]
+    },
+    {
+      label: 'Help',
+      role: 'help',
+      submenu: [
+        {
+          label: 'About SoundCleod',
+          click() {
+            prefman.showAbout();
+          },
+          visible: process.platform !== 'darwin'
+        }
+
+      ]
     }
   ]