docs: Update docs for keyboard shortcuts (#29207)

* Update docs for keyboard shortcuts

* Add a fiddle for web-apis

* Apply suggestions from code review

Co-authored-by: Erick Zhao <erick@hotmail.ca>

* Cleanup a few formatting errors and missed copies

* Add descriptions to index.html

* Focus on renderer

Co-authored-by: Erick Zhao <erick@hotmail.ca>

docs/fiddles/features/keyboard-shortcuts/web-apis/main.js

@@ -0,0 +1,35 @@
+// Modules to control application life and create native browser window
+const {app, BrowserWindow} = require('electron')
+const path = require('path')
+
+function createWindow () {
+  // Create the browser window.
+  const mainWindow = new BrowserWindow({
+    width: 800,
+    height: 600,
+  })
+
+  // and load the index.html of the app.
+  mainWindow.loadFile('index.html')
+
+}
+
+// This method will be called when Electron has finished
+// initialization and is ready to create browser windows.
+// Some APIs can only be used after this event occurs.
+app.whenReady().then(() => {
+  createWindow()
+  
+  app.on('activate', function () {
+    // On macOS it's common to re-create a window in the app when the
+    // dock icon is clicked and there are no other windows open.
+    if (BrowserWindow.getAllWindows().length === 0) createWindow()
+  })
+})
+
+// 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 () {
+  if (process.platform !== 'darwin') app.quit()
+})