Support sphinx 4.2
Support sphinx 4.2

Add the sphinx documentation options provided by sphinx 4.2. Otherwise
the search will produce URLs with `undefined` instead of `.html`:

```
ref/states/all/salt.states.fileundefined?highlight=file#module-salt.states.file
```

Signed-off-by: Benjamin Drung <86a6db991ec5c1a96f98c92b98df9d547d7c8c84@ionos.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt