How to add custom fields to files

[texnixe]

Not that I know of, but that would be good feature, sth. like:

files:
 type: 
  - image
    fields:
      title:
        label: Title
        type: text
      alt_text:
        label: Alt Text
        type: text
  - document  
     fields:
        label: Title
        type: text
...