gh-152912: Fix stale C-API doc for PySys_AddAuditHook exception suppression

Doc/c-api/sys.rst still said Exception for the suppression behavior, matching the buggy Python-API code at sysmodule.c:530. The C-API code at sysmodule.c:486 has used PyExc_RuntimeError since 3.8.1 (commit bea33f5), but the C-API doc was never updated. Align it with both the code and Doc/library/sys.rst.

Author: k00shi

Doc/c-api/sys.rst

@@ -433,7 +433,12 @@ accessible to C code.  They all work with the current interpreter thread's
    This function is safe to call before :c:func:`Py_Initialize`. When called
    after runtime initialization, existing audit hooks are notified and may
    silently abort the operation by raising an error subclassed from
-   :class:`Exception` (other errors will not be silenced).
+   :class:`RuntimeError` (other errors will not be silenced).
+
+   .. versionchanged:: 3.8.1
+
+      Exceptions derived from :class:`Exception` but not :class:`RuntimeError`
+      are no longer suppressed.
 
    The hook function is always called with an :term:`attached thread state` by
    the Python interpreter that raised the event.
@@ -447,7 +452,7 @@ accessible to C code.  They all work with the current interpreter thread's
 
       If the interpreter is initialized, this function raises an auditing event
       ``sys.addaudithook`` with no arguments. If any existing hooks raise an
-      exception derived from :class:`Exception`, the new hook will not be
+      exception derived from :class:`RuntimeError`, the new hook will not be
       added and the exception is cleared. As a result, callers cannot assume
       that their hook has been added unless they control all existing hooks.