display the 'doc' field from the .ksy file in the JSON
My requirements: Convert the .ksy file into a JSON file that is more readable.

Is it possible to display the 'doc' field from the .ksy file in the JSON?
If not, are there any other methods? For example, defining a field under 'instances' and setting its value to a fixed string.

```ksy
    instances:
      doc:
        value: 'the document of field'
```
