pythongh-102778: update documentation of PyErr_PrintEx regarding sys.last_exc

Author: iritkatriel

Doc/c-api/exceptions.rst

@@ -60,9 +60,14 @@ Printing and clearing
    Call this function **only** when the error indicator is set.  Otherwise it
    will cause a fatal error!
 
-   If *set_sys_last_vars* is nonzero, the variables :data:`sys.last_type`,
-   :data:`sys.last_value` and :data:`sys.last_traceback` will be set to the
-   type, value and traceback of the printed exception, respectively.
+   If *set_sys_last_vars* is nonzero, the variable :data:`sys.last_exc` is
+   set to the printed exception. For backwards compatibility, the
+   deprecated variables :data:`sys.last_type`, :data:`sys.last_value` and
+   :data:`sys.last_traceback` will also be set to the type, value and
+   traceback of this exception, respectively.
+
+   .. versionchanged:: 3.12
+   :data:`sys.last_exc` was added.
 
 
 .. c:function:: void PyErr_Print()