gcc-13/changes.html: Add nvptx's --with-arch

diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html
index 390193ca..f113e443 100644
--- a/htdocs/gcc-13/changes.html
+++ b/htdocs/gcc-13/changes.html
@@ -209,7 +209,18 @@ a work-in-progress.</p>
 
 <!-- <h3 id="nios2">Nios II</h3> -->
 
-<!-- <h3 id="nvptx">NVPTX</h3> -->
+<h3 id="nvptx">NVPTX</h3>
+<ul>
+  <li>The default value for the <a
+      href="https://gcc.gnu.org/onlinedocs/gcc/Nvidia-PTX-Options.html"><code>
+      -march</code></a> option can be now changed when <a
+      href="https://gcc.gnu.org/install/">building GCC</a> using the
+      <a href="https://gcc.gnu.org/install/specific.html#nvptx-x-none">
+      <code>--with-arch=</code></a> flag; if not specified, GCC defaults to
+      <code>sm_30</code>. GCC's target libraries are build both with
+      <code>sm_30</code> and the specified target architecture.
+  </li>
+</ul>
 
 <!-- <h3 id="hppa">PA-RISC</h3> -->