Fix alternative solution to add and remove a CSS class (#4027) (#4072)

* Fix alternative solution to add and remove a CSS class (#4027)

* Update reacting-to-input-with-state.md

Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

beta/src/pages/learn/reacting-to-input-with-state.md

@@ -633,6 +633,7 @@ export default function Picture() {
           className="picture picture--active"
           alt="Rainbow houses in Kampung Pelangi, Indonesia"
           src="https://i.imgur.com/5qwVYb1.jpeg"
+          onClick={e => e.stopPropagation()}
         />
       </div>
     );