pythongh-98586: add whatsnew entry, related documentation fix

PR python#98587 addressing issue python#98586 lacked a "what's new" entry.

While making those changes, I noticed an inconsistency in how
``PY_VECTORCALL_ARGUMENTS_OFFSET`` is declared in the underlying Sphinx
markup when compared to other macro constants like
``Py_TPFLAGS_HAVE_VECTORCALL``. This PR fixes that as well, which should
connect a few currently broken cross-references

Author: wjakob

Doc/c-api/call.rst

@@ -93,7 +93,7 @@ This is a pointer to a function with the following signature:
    and they must be unique.
    If there are no keyword arguments, then *kwnames* can instead be *NULL*.
 
-.. c:macro:: PY_VECTORCALL_ARGUMENTS_OFFSET
+.. data:: PY_VECTORCALL_ARGUMENTS_OFFSET
 
    If this flag is set in a vectorcall *nargsf* argument, the callee is allowed
    to temporarily change ``args[-1]``. In other words, *args* points to

Doc/whatsnew/3.12.rst

@@ -622,6 +622,18 @@ New Features
   ``__dict__`` and weakrefs with less bookkeeping,
   using less memory and with faster access.
 
+* API for performing calls using the
+  :ref:`the vectorcall protocol <vectorcall>` was added to the
+  :ref:`Limited API <stable>`:
+
+  * :c:func:`PyObject_Vectorcall`
+  * :c:func:`PyObject_VectorcallMethod`
+  * :const:`Py_TPFLAGS_HAVE_VECTORCALL`
+
+  Together with the previous change, this covers both receiving and outgoing
+  ends of the vector call protocol. (Contributed by Wenzel Jakob in
+  :gh:`98586`.)
+
 * Added two new public functions,
   :c:func:`PyEval_SetProfileAllThreads` and
   :c:func:`PyEval_SetTraceAllThreads`, that allow to set tracing and profiling

Misc/NEWS.d/next/Core and Builtins/2022-10-24-10-30-30.gh-issue-98586.Tha5Iy.rst

@@ -1,6 +1,6 @@
 Added the methods :c:func:`PyObject_Vectorcall` and
 :c:func:`PyObject_VectorcallMethod` to the :ref:`Limited API <stable>` along
-with the auxiliary macro constant :c:macro:`PY_VECTORCALL_ARGUMENTS_OFFSET`.
+with the auxiliary macro constant :const:`PY_VECTORCALL_ARGUMENTS_OFFSET`.
 
 The availability of these functions enables more efficient :PEP:`590` vector
 calls from binary extension modules that avoid argument boxing/unboxing