Fix useEffect syntax error in conditional dragging example

Addresses #224

Fixed incorrect useEffect syntax in the conditional dragging documentation.

Changed:
  useEffect({
To:
  useEffect(() => {

useEffect expects a callback function as its first argument, not an object.

Author: Pepper Pancoast

packages/documentation/constellation/05-core-package/00-adapters/00-element/about.mdx

@@ -159,7 +159,7 @@ function noop(){};
 function Item({isDraggingEnabled}: {isDraggingEnabled: boolean}) {
   const ref = useRef();
 
-  useEffect({
+  useEffect(() => {
     // when disabled, don't make the element draggable
     // this will allow a parent draggable to still be dragged
     if(!isDraggingEnabled) {