[clang] [clang][docs] Fix DR staus for P2280R4 (PR #127166)

[A. Jiang via cfe-commits]

https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/127166

P2280R4 is officially a defect report. Although Clang 20 only implementated it for C++23 and later, and #95474 accidently removed the DR status in `cxx_status.html`. I think we should mention that it is a DR but not backported yet.

>From a2fc3d0550ab22e1a4273dc2debfda23df7cad6f Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Fri, 14 Feb 2025 14:03:23 +0800
Subject: [PATCH] [clang][docs] Fix DR staus for P2280R4

P2280R4 is officially a defect report. Although Clang 20 only implementated it
for C++23 and later. I think we should mention that it is a DR but not backported yet.
---
 clang/www/cxx_status.html | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html
index 0fc3b1d314698..70490b2e4331f 100755
--- a/clang/www/cxx_status.html
+++ b/clang/www/cxx_status.html
@@ -439,8 +439,8 @@ <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 class="unreleased" align="center">Clang 20</td>
+      <td><a href="https://wg21.link/P2280R4">P2280R4</a> (<a href="#dr">DR</a>)</td>
+      <td class="unreleased" align="center">Clang 20 <a href="#p2280">(12)</a></td>
     </tr>
     <tr>
       <td>static <code>operator()</code></td>
@@ -510,6 +510,12 @@ <h2 id="cxx23">C++23 implementation status</h2>
       <td class="full" align="center">Yes</td>
     </tr>
 </table>
+
+<p>
+<span id="p2280">(12): In Clang 20, this change is not yet retroactively
+applied to pre-C++23 modes.
+</span>
+</p>
 </details>