Bug?  `ignore-words-list` seems to have no effect

Am I doing something wrong?  How can I get it to stop flagging `MSDOS` as an error?  `ignore-words-list` seems to have no effect

```
> codespell
./src/keyszer/models/key.py:161: MSDOS ==> MS-DOS
```

My config:

```ini
[codespell]
ignore-words-list = MSDOS
skip = .venv,.git,build,keyszer.egg-info
```