bpo-33407: Implement Py_DEPRECATED() on MSVC (GH-8980)

diff --git a/Doc/c-api/intro.rst b/Doc/c-api/intro.rst
index 672936a..a1c8d34 100644
--- a/Doc/c-api/intro.rst
+++ b/Doc/c-api/intro.rst
@@ -160,6 +160,18 @@
 
    .. versionadded:: 3.4
 
+.. c:macro:: Py_DEPRECATED(version)
+
+   Use this for deprecated declarations.  The macro must be placed before the
+   symbol name.
+
+   Example::
+
+      Py_DEPRECATED(3.8) PyAPI_FUNC(int) Py_OldFunction(void);
+
+   .. versionchanged:: 3.8
+      MSVC support was added.
+
 
 .. _api-objects: