docs: add IPC doc (#32059)

* docs: add IPC doc

* fix: use "string" primitive

* use 'string' ipcrenderer

* use "number" primitive

* Update docs/tutorial/ipc.md

Co-authored-by: Jeremy Rose <nornagon@nornagon.net>

* Update docs/tutorial/ipc.md

Co-authored-by: Jeremy Rose <nornagon@nornagon.net>

* add code sample

Co-authored-by: Jeremy Rose <nornagon@nornagon.net>

docs/fiddles/ipc/pattern-2/main.js

@@ -0,0 +1,32 @@
+const {app, BrowserWindow, ipcMain} = require('electron')
+const path = require('path')
+
+async function handleFileOpen() {
+  const { canceled, filePaths } = await dialog.showOpenDialog()
+  if (canceled) {
+    return
+  } else {
+    return filePaths[0]
+  }
+}
+
+function createWindow () {
+  const mainWindow = new BrowserWindow({
+    webPreferences: {
+      preload: path.join(__dirname, 'preload.js')
+    }
+  })
+  mainWindow.loadFile('index.html')
+}
+
+app.whenReady().then(() => {
+  ipcMain.handle('dialog:openFile', handleFileOpen)
+  createWindow()
+  app.on('activate', function () {
+    if (BrowserWindow.getAllWindows().length === 0) createWindow()
+  })
+})
+
+app.on('window-all-closed', function () {
+  if (process.platform !== 'darwin') app.quit()
+})