fix some class headings

docs/api/menu-item.md

@@ -1,4 +1,4 @@
-# MenuItem
+## Class: MenuItem
 
 > Add items to native application menus and context menus.
 
@@ -6,10 +6,6 @@ Process: [Main](../tutorial/quick-start.md#main-process)
 
 See [`Menu`](menu.md) for examples.
 
-## Class: MenuItem
-
-Create a new `MenuItem` with the following method:
-
 ### `new MenuItem(options)`
 
 * `options` Object

docs/api/menu.md

@@ -1,4 +1,4 @@
-# Menu
+## Class: Menu
 
 > Create native application menus and context menus.
 
@@ -217,8 +217,6 @@ window.addEventListener('contextmenu', (e) => {
 </script>
 ```
 
-## Class: Menu
-
 ### `new Menu()`
 
 Creates a new menu.

docs/api/tray.md

@@ -1,9 +1,11 @@
-# Tray
+## Class: Tray
 
 > Add icons and context menus to the system's notification area.
 
 Process: [Main](../tutorial/quick-start.md#main-process)
 
+`Tray` is an [EventEmitter][event-emitter].
+
 ```javascript
 const {app, Menu, Tray} = require('electron')
 
@@ -55,9 +57,6 @@ app.on('ready', () => {
 If you want to keep exact same behaviors on all platforms, you should not
 rely on the `click` event and always attach a context menu to the tray icon.
 
-## Class: Tray
-
-`Tray` is an [EventEmitter][event-emitter].
 
 ### `new Tray(image)`