[gcc r16-2352] libstdc++: Document new generated header

[Jonathan Wakely]

https://gcc.gnu.org/g:717e20dddd84c8f275c4731ad3da16cc71aa923c

commit r16-2352-g717e20dddd84c8f275c4731ad3da16cc71aa923c
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Jul 18 17:43:08 2025 +0100

    libstdc++: Document new generated header
    
    libstdc++-v3/ChangeLog:
    
            * doc/xml/manual/build_hacking.xml: Document that
            windows_zones-map.h is a generated file.
            * doc/html/manual/appendix_porting.html: Regenerate.

Diff:
---
 libstdc++-v3/doc/html/manual/appendix_porting.html |  7 +++++++
 libstdc++-v3/doc/xml/manual/build_hacking.xml      | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/libstdc++-v3/doc/html/manual/appendix_porting.html b/libstdc++-v3/doc/html/manual/appendix_porting.html
index e0f52dba6d2a..887fa50caa4c 100644
--- a/libstdc++-v3/doc/html/manual/appendix_porting.html
+++ b/libstdc++-v3/doc/html/manual/appendix_porting.html
@@ -497,4 +497,11 @@ baseline file.
    See <a class="xref" href="configure.html" title="Configure">Configuring</a> for the
    <code class="code">--with-libstdcxx-zoneinfo</code> option that determines whether
    this file is used.
+   </p></li><li class="listitem"><p>
+   The header file
+   <code class="filename">src/c++20/windows_zones-map.h</code>
+   is generated by the Python script
+   <code class="filename">scripts/gen_windows_zones_map.py</code>
+   using the XML file <a class="link" href="https://github.com/unicode-org/cldr/blob/main/common/supplemental/windowsZones.xml" target="_top">https://github.com/unicode-org/cldr/blob/main/common/supplemental/windowsZones.xml</a>
+   from the Unicode CLDR Project.
    </p></li></ul></div></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="source_design_notes.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="appendix.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="documentation_hacking.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Design Notes </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Writing and Generating Documentation</td></tr></table></div></body></html>
\ No newline at end of file
diff --git a/libstdc++-v3/doc/xml/manual/build_hacking.xml b/libstdc++-v3/doc/xml/manual/build_hacking.xml
index 077c0632a791..20de49f553c0 100644
--- a/libstdc++-v3/doc/xml/manual/build_hacking.xml
+++ b/libstdc++-v3/doc/xml/manual/build_hacking.xml
@@ -742,6 +742,17 @@ baseline file.
    this file is used.
    </para>
  </listitem>
+ <listitem>
+   <para>
+   The header file
+   <filename class="headerfile">src/c++20/windows_zones-map.h</filename>
+   is generated by the Python script
+   <filename>scripts/gen_windows_zones_map.py</filename>
+   using the XML file <link xmlns:xlink="http://www.w3.org/1999/xlink"
+     xlink:href="https://github.com/unicode-org/cldr/blob/main/common/supplemental/windowsZones.xml"/>
+   from the Unicode CLDR Project.
+   </para>
+ </listitem>
 </itemizedlist>
 
 </section> <!-- Generated files -->