Mariabackup docs for privileges incomplete / outdated for rocksdb backups

OS: Linux Debian-93-stretch-64-minimal 4.9.0-8-amd64 #1 SMP Debian 4.9.144-3.1 (2019-02-19) x86_64

MariaDB: 10.2.21-MariaDB-10.2.21+maria~stretch-log (binary distribution with plugin-rocksdb)

mariabackup version: mariabackup based on MariaDB server 10.2.21-MariaDB debian-linux-gnu (x86_64)

User created according to the info found at https://mariadb.com/kb/en/library/mariabackup-overview/#authentication-and-privileges

When running mariabackup the following error message appears:
[..] Obtaining rocksdb checkpoint lock.
Error: failed to execute query SET GLOBAL rocksdb_create_checkpoint='/data/rocksdb/mariabackup-checkpoint': Access denied; you need (at least one of) the SUPER privilege(s) for this operation

I will try to grant the SUPER privilege to the user and re-run the backup. Would be great to include that in the docs.