[libc++] Enable segmented iterator optimizations for join_view::iterator

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D138413

NOKEYCHECK=True
GitOrigin-RevId: 21f4232dd963c449231f03a90836071202fd134a
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 0d5e95e..c0e5542 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -79,6 +79,9 @@
 - `D122780 <https://reviews.llvm.org/D122780>`_ Improved the performance of std::sort
 - The ``ranges`` versions of ``copy``, ``move``, ``copy_backward`` and ``move_backward`` are now also optimized for
   ``std::deque<>::iterator``, which can lead to up to 20x performance improvements on certain algorithms.
+- The ``std`` and ``ranges`` versions of ``copy``, ``move``, ``copy_backward`` and ``move_backward`` are now also
+  optimized for ``join_view::iterator``, which can lead to up to 20x performance improvements on certain combinations of
+  iterators and algorithms.
 
 Deprecations and Removals
 -------------------------