PEP 800: Note that ty now supports @disjoint_base, note typing_extensions release (#4560)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>

Author: AlexWaygood

peps/pep-0800.rst

@@ -371,10 +371,12 @@ explain to users why type checkers treat certain branches as unreachable.
 Reference Implementation
 ========================
 
-The runtime implementation of the ``@disjoint_base`` decorator will be available in
-typing-extensions 4.15.0.
+The runtime implementation of the ``@disjoint_base`` decorator is available in
+`typing-extensions 4.15.0 <https://pypi.org/project/typing-extensions/4.15.0/>`__.
 `python/mypy#19678 <https://github.com/python/mypy/pull/19678>`__
 implements support for disjoint bases in mypy and in the stubtest tool.
+`astral-sh/ruff#20084 <https://github.com/astral-sh/ruff/pull/20084>`__
+implements support for disjoint bases in the ty type checker.
 
 Appendix
 ========