[clang][NFC] order C++ standards in reverse in release notes (#104866)

Noticed that the release notes currently have a weird order: C++17,
C++14(!), C++20, C++23, C++2c. Reorder them in reverse chronological
order, which also matches the [status
page](https://clang.llvm.org/cxx_status.html).

Author: h-vetinari

clang/docs/ReleaseNotes.rst

@@ -107,19 +107,6 @@ C++ Language Changes
   constant expression. Supports the `V.xyzw` syntax and other tidbits
   as seen in OpenCL. Selecting multiple elements is left as a future work.
 
-C++17 Feature Support
-^^^^^^^^^^^^^^^^^^^^^
-
-C++14 Feature Support
-^^^^^^^^^^^^^^^^^^^^^
-
-C++20 Feature Support
-^^^^^^^^^^^^^^^^^^^^^
-
-C++23 Feature Support
-^^^^^^^^^^^^^^^^^^^^^
-- Removed the restriction to literal types in constexpr functions in C++23 mode.
-
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
@@ -131,6 +118,13 @@ C++2c Feature Support
 
 - Implemented `P2893R3 Variadic Friends <https://wg21.link/P2893>`_
 
+C++23 Feature Support
+^^^^^^^^^^^^^^^^^^^^^
+- Removed the restriction to literal types in constexpr functions in C++23 mode.
+
+C++20 Feature Support
+^^^^^^^^^^^^^^^^^^^^^
+
 Resolutions to C++ Defect Reports
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^