Show element used for hx-indicator in value-select example code (#2275)

Show element used for hx-indicator in example code

Code examples does not include element with class `.htmx-indicator` used for hx-indicator attribute

www/content/examples/value-select.md

@@ -25,6 +25,7 @@ Here is the code:
       <option value="a1">A1</option>
       ...
     </select>
+    <img class="htmx-indicator" width="20" src="/img/bars.svg">
 </div>
 ```