gh-104003: Implement PEP 702 (#104004)

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Doc/library/warnings.rst

@@ -522,6 +522,56 @@ Available Functions
    and calls to :func:`simplefilter`.
 
 
+.. decorator:: deprecated(msg, *, category=DeprecationWarning, stacklevel=1)
+
+   Decorator to indicate that a class, function or overload is deprecated.
+
+   When this decorator is applied to an object,
+   deprecation warnings may be emitted at runtime when the object is used.
+   :term:`static type checkers <static type checker>`
+   will also generate a diagnostic on usage of the deprecated object.
+
+   Usage::
+
+      from warnings import deprecated
+      from typing import overload
+
+      @deprecated("Use B instead")
+      class A:
+          pass
+
+      @deprecated("Use g instead")
+      def f():
+          pass
+
+      @overload
+      @deprecated("int support is deprecated")
+      def g(x: int) -> int: ...
+      @overload
+      def g(x: str) -> int: ...
+
+   The warning specified by *category* will be emitted at runtime
+   on use of deprecated objects. For functions, that happens on calls;
+   for classes, on instantiation and on creation of subclasses.
+   If the *category* is ``None``, no warning is emitted at runtime.
+   The *stacklevel* determines where the
+   warning is emitted. If it is ``1`` (the default), the warning
+   is emitted at the direct caller of the deprecated object; if it
+   is higher, it is emitted further up the stack.
+   Static type checker behavior is not affected by the *category*
+   and *stacklevel* arguments.
+
+   The deprecation message passed to the decorator is saved in the
+   ``__deprecated__`` attribute on the decorated object.
+   If applied to an overload, the decorator
+   must be after the :func:`@overload <typing.overload>` decorator
+   for the attribute to exist on the overload as returned by
+   :func:`typing.get_overloads`.
+
+   .. versionadded:: 3.13
+      See :pep:`702`.
+
+
 Available Context Managers
 --------------------------