[3.14] gh-141004: Document deprecated aliases for memory allocation (GH-141146) (GH-141288)

gh-141004: Document deprecated aliases for memory allocation (GH-141146)
(cherry picked from commit 1d738de)

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Author: miss-islington

Doc/c-api/allocation.rst

@@ -140,10 +140,6 @@ Allocating Objects on the Heap
       * :c:member:`~PyTypeObject.tp_alloc`
 
 
-.. c:function:: void PyObject_Del(void *op)
-
-   Same as :c:func:`PyObject_Free`.
-
 .. c:var:: PyObject _Py_NoneStruct
 
    Object which is visible in Python as ``None``.  This should only be accessed
@@ -156,3 +152,35 @@ Allocating Objects on the Heap
    :ref:`moduleobjects`
       To allocate and create extension modules.
 
+
+Deprecated aliases
+^^^^^^^^^^^^^^^^^^
+
+These are :term:`soft deprecated` aliases to existing functions and macros.
+They exist solely for backwards compatibility.
+
+
+.. list-table::
+   :widths: auto
+   :header-rows: 1
+
+   * * Deprecated alias
+     * Function
+   * * .. c:macro:: PyObject_NEW(type, typeobj)
+     * :c:macro:`PyObject_New`
+   * * .. c:macro:: PyObject_NEW_VAR(type, typeobj, n)
+     * :c:macro:`PyObject_NewVar`
+   * * .. c:macro:: PyObject_INIT(op, typeobj)
+     * :c:func:`PyObject_Init`
+   * * .. c:macro:: PyObject_INIT_VAR(op, typeobj, n)
+     * :c:func:`PyObject_InitVar`
+   * * .. c:macro:: PyObject_MALLOC(n)
+     * :c:func:`PyObject_Malloc`
+   * * .. c:macro:: PyObject_REALLOC(p, n)
+     * :c:func:`PyObject_Realloc`
+   * * .. c:macro:: PyObject_FREE(p)
+     * :c:func:`PyObject_Free`
+   * * .. c:macro:: PyObject_DEL(p)
+     * :c:func:`PyObject_Free`
+   * * .. c:macro:: PyObject_Del(p)
+     * :c:func:`PyObject_Free`