[backup or migration] paperless-ngx

Paperless uses 4 volumes:

    paperless_media: This is where your documents are stored.
    paperless_data: This is where auxiliary data is stored. This folder also contains the SQLite database, if you use it.
    paperless_pgdata: Exists only if you use PostgreSQL and contains the database.
    paperless_dbdata: Exists only if you use MariaDB and contains the database.

위 폴더만 백업하면 된다고 한다.