fix "at the following" typo

should be "add the following"

docs/documentation/components/modal.html

@@ -222,7 +222,7 @@ document.addEventListener('DOMContentLoaded', () => {
   <h4>1. Add the HTML for the modal</h4>
 
   <p>
-    At the end of your page, before the closing <code>&lt;/body&gt;</code> tag, at the following HTML snippet:
+    At the end of your page, before the closing <code>&lt;/body&gt;</code> tag, add the following HTML snippet:
   </p>
 </div>