bpo-43109: configure doc: LTO requires "ar" on macOS (GH-26349)

(cherry picked from commit 63f17c252ab1b9357c5f022296213c42d9629458)

Co-authored-by: Victor Stinner <vstinner@python.org>
diff --git a/Doc/using/configure.rst b/Doc/using/configure.rst
index c37540c..177f25f 100644
--- a/Doc/using/configure.rst
+++ b/Doc/using/configure.rst
@@ -175,8 +175,8 @@
 
    Enable Link Time Optimization (LTO) in any build (disabled by default).
 
-   The C compiler Clang requires ``llvm-ar`` for LTO, as well as an LTO-aware
-   linker (``ld.gold`` or ``lld``).
+   The C compiler Clang requires ``llvm-ar`` for LTO (``ar`` on macOS), as well
+   as an LTO-aware linker (``ld.gold`` or ``lld``).
 
    .. versionadded:: 3.6