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/renderer.js

@@ -0,0 +1,7 @@
+function handleKeyPress (event) {
+  // You can put code here to handle the keypress.
+  document.getElementById("last-keypress").innerText = event.key
+  console.log(`You pressed ${event.key}`)
+}
+
+window.addEventListener('keyup', handleKeyPress, true)