docs: use electron/main & electron/renderer imports in fiddles (#39666)

docs/fiddles/system/protocol-handler/launch-app-from-URL-in-another-app/preload.js

@@ -1,11 +1,5 @@
-// All of the Node.js APIs are available in the preload process.
-// It has the same sandbox as a Chrome extension.
-const { contextBridge, ipcRenderer } = require('electron')
+const { contextBridge, ipcRenderer } = require('electron/renderer')
 
-// Set up context bridge between the renderer process and the main process
-contextBridge.exposeInMainWorld(
-  'shell',
-  {
-    open: () => ipcRenderer.send('shell:open')
-  }
-)
+contextBridge.exposeInMainWorld('shell', {
+  open: () => ipcRenderer.send('shell:open')
+})