[wwwdocs] Document libstdc++ support for generic unordered lookup

[Jonathan Wakely via Gcc-patches]

This should have been in the GCC 11 release notes, pushed now.


commit bbbf05e7f3d3e7a74d23e8cc252ebae895158abe
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Jun 7 10:27:00 2021 +0100

    Document libstdc++ support for generic unordered lookup

diff --git a/htdocs/gcc-11/changes.html b/htdocs/gcc-11/changes.html
index ef533e31..97606174 100644
--- a/htdocs/gcc-11/changes.html
+++ b/htdocs/gcc-11/changes.html
@@ -526,6 +526,7 @@ You may also want to check out our
         and <code>&lt;semaphore&gt;</code></li>
       <li><code>&lt;syncstream&gt;</code></li>
       <li>Efficient access to <code>basic_stringbuf</code>'s buffer.</li>
+      <li>Heterogeneous lookup in unordered containers.</li>
     </ul>
   </li>
   <li>Experimental C++23 support, including: