Update multiple-scenes.html

Fix markup.

manual/en/multiple-scenes.html

@@ -622,7 +622,7 @@ render the scene for this area, then copy the result to the area's canvas.</p>
 <p></p>
 <p>One other advantage to this solution is you could potentially use
 <a href="https://developer.mozilla.org/en-US/docs/Web/API/OffscreenCanvas"><code class="notranslate" translate="no">OffscreenCanvas</code></a>
-to render from a web worker and still use this technique.
+to render from a web worker and still use this technique.</p>
 
         </div>
       </div>