[3.14] gh-141004: Document symbol visibility macros (PyAPI_DATA, Py_EXPORTED_SYMBOL, Py_LOCAL_SYMBOL,Py_IMPORTED_SYMBOL) (GH-143508)

[3.14] gh-141004: Document symbol visibility macros (PyAPI_DATA, Py_EXPORTED_SYMBOL, Py_LOCAL_SYMBOL,Py_IMPORTED_SYMBOL) (GH-143508) #231559