pythongh-101291: Add versionadded directives for PyUnstable_Long_* (pythonGH-125384)

(cherry picked from commit c6d7b64)

Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>

Author: skirpichev

Doc/c-api/long.rst

@@ -350,10 +350,15 @@ distinguished from a number.  Use :c:func:`PyErr_Occurred` to disambiguate.
    Exactly what values are considered compact is an implementation detail
    and is subject to change.
 
+   .. versionadded:: 3.12
+
+
 .. c:function:: Py_ssize_t PyUnstable_Long_CompactValue(const PyLongObject* op)
 
    If *op* is compact, as determined by :c:func:`PyUnstable_Long_IsCompact`,
    return its value.
 
    Otherwise, the return value is undefined.
 
+   .. versionadded:: 3.12
+