Help: Add release note for windows-arm64 binary

Since commit 41ea4d4de8 (ci: Rebuild Qt 6.3.0 windows-arm64 dependency
with LLVM/Clang, 2022-06-17) the release binary package now includes a
working `cmake-gui`, and is ready for general usage.

Fixes: #21902

Help/release/3.24.rst

@@ -345,4 +345,6 @@ Other Changes
   SLA to the ``.dmg`` packages.  This was removed because macOS 12 deprecated
   the tools used to attach ``.dmg`` resources.
 
+* A precompiled Windows ``arm64`` binary is now provided on `cmake.org`_.
+
 .. _`cmake.org`: https://cmake.org/download/