Empty Document field

The emptyDocument is a mechanism to trigger a collection or singleton to output .mdoc files even if there is no real document field in the schema.

Use this in conjunction with the format.contentField option.

Usage example

schema: {
  // Other fields (but no `document`)...
  fakeDocument: fields.emptyDocument()
format: {
  contentField: 'fakeDocument'

Instead of generating .yaml or .json files, the collection or singleton will output .mdoc files with frontmatter data and an empty content body.