docs: fix explanation of darwin auto-quit prevention (#394)

main.js

@@ -32,10 +32,10 @@ app.whenReady().then(() => {
   })
 })
 
-// Quit when all windows are closed.
+// Quit when all windows are closed, except on macOS. There, it's common
+// for applications and their menu bar to stay active until the user quits
+// explicitly with Cmd + Q.
 app.on('window-all-closed', function () {
-  // On macOS it is common for applications and their menu bar
-  // to stay active until the user quits explicitly with Cmd + Q
   if (process.platform !== 'darwin') app.quit()
 })