[PATCH gcc-wwwdocs] gcc-16: document some more libstdc++ changes

[Patrick Palka]

OK to push?
---
 htdocs/gcc-16/changes.html | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/htdocs/gcc-16/changes.html b/htdocs/gcc-16/changes.html
index fc100056..269bcc29 100644
--- a/htdocs/gcc-16/changes.html
+++ b/htdocs/gcc-16/changes.html
@@ -354,6 +354,12 @@ struct Affected : E
     C++17 mode.
   </li>
  
+  <li>
+    <code>std::regex</code> execution has been rewritten to use a heap-based
+    stack instead of the system stack, avoiding stack overflows when matching
+    larger strings.
+  </li>
+
   <li>Improved support for C++20, including:
     <ul>
     <li>
@@ -403,6 +409,9 @@ struct Affected : E
     <li>
       <code>ranges::starts_with</code> and <code>ranges::ends_with</code>.
     </li>
+    <li>
+      <code>ranges::shift_left</code> and <code>ranges::shift_right</code>.
+    </li>
     <li><code>std::allocator_traits::allocate_at_least</code>.</li>
     </ul>
   </li>
-- 
2.54.0.rc1.54.g60f07c4f5c