For now in this structure, most of the long comments on items are actually in the header above the structure. Can you add the comments at the top instead of inline maybe something like this:

```
- `notify_cb` is an optional callback function, notifying the consumer of
   which files are being examined as the diff is generated
- `notify_payload` is payload data to pass to the `notify_cb` function
```

Your wording is fine, but now the header for the structure looks like it is out of sync with the definition.