[Clang] Mark that P2280R4 was approved as a dr in the status page

Author: cor3ntin

clang/www/cxx_status.html

@@ -475,7 +475,7 @@ <h2 id="cxx23">C++23 implementation status</h2>
     </tr>
     <tr>
       <td>Using unknown pointers and references in constant expressions</td>
-      <td><a href="https://wg21.link/P2280R4">P2280R4</a></td>
+      <td><a href="https://wg21.link/P2280R4">P2280R4</a> (<a href="#dr">DR</a>)</td>
       <td class="unreleased" align="center">Clang 20</td>
     </tr>
     <tr>