Separate `assets/` folder for each note

[leowill01]

id like to request the feature addition of having a separate assets/ folder for each note. this could take the form of:

1. assets-${filename}/
2. but preferably there would be an option to make a separate 'document' folder for each note, with the assets/ and note-name.md within so all the notes and their asset folders are mixed together in the main export folder:

${note_name}/
|-- ${note_name}.md
`-- assets/