docs(keyboard): clarify hide on keyboard open

js/utils/keyboard.js

@@ -27,6 +27,20 @@
  *   <div id="google-map"></div>
  * </div>
  * ```
+ *
+ * Note: For performance reasons, elements will not be hidden for 400ms after the start of the `native.keyboardshow` event
+ * from the Ionic Keyboard plugin. If you would like them to disappear immediately, you could do something
+ * like:
+ *
+ * ```js
+ *   window.addEventListener('native.keyboardshow', function(){
+ *     document.body.classList.add('keyboard-open');
+ *   });
+ * ```
+ * This adds the same `keyboard-open` class that is normally added by Ionic 400ms after the keyboard
+ * opens. However, bear in mind that adding this class to the body immediately may cause jank in any
+ * animations on Android that occur when the keyboard opens (for example, scrolling any obscured inputs into view).
+ *
  * ----------
  *
  * ### Plugin Usage