Enabling Enhanced Notes in scratch org

An answer was posted to a similar question in the Salesforce DX group in the Salesforce Trailblazer community. For posterity, the relevant feature id is "NotesReservedPref01", hence:

"orgPreferences" : {
  "enabled": ["ChatterEnabled", "NotesReservedPref01"]
}

in the scratch org definition.

Nowadays, here is the setting:

{
    "settings": {
        "enhancedNotesSettings": {
            "enableEnhancedNotes": true
        }
    }
}

As @JasonClark said, the orgPreferences has been deprecated in Winter 19. He was on the right track, but the settings should now use lowerCamelCase and the "n" should be lowercase.

"settings" : "orgPreferenceSettings" : { "notesReservedPref01" : true }