[Clang] Update release notes

Update release notes.
This is a follow-up to https://reviews.llvm.org/D146178

Differential revision: https://reviews.llvm.org/D149906

clang/docs/ReleaseNotes.rst

@@ -77,8 +77,13 @@ C++ Language Changes
 
 C++20 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
-- Support for out-of-line definitions of constrained templates has been improved.
-  This partially fixes `#49620 <https://github.com/llvm/llvm-project/issues/49620>`_.
+- Implemented the rule introduced by `CA104 <https://wg21.link/P2103R0>`_  for comparison of
+  constraint-expressions. Improved support for out-of-line definitions of constrained templates.
+  This fixes:
+  `#49620 <https://github.com/llvm/llvm-project/issues/49620>`_,
+  `#60231 <https://github.com/llvm/llvm-project/issues/60231>`_,
+  `#61414 <https://github.com/llvm/llvm-project/issues/60414>`_,
+  `#61809 <https://github.com/llvm/llvm-project/issues/61809>`_.
 - Lambda templates with a requires clause directly after the template parameters now parse
   correctly if the requires clause consists of a variable with a dependent type.
   (`#61278 <https://github.com/llvm/llvm-project/issues/61278>`_)