adding clarification to neo4j-admin backup command description (#1227) (#1237)

Cherry-picked from #1227

Co-authored-by: Phil Wright <[email protected]>

Author: renetapopova

modules/ROOT/pages/backup-restore/online-backup.adoc

@@ -128,11 +128,14 @@ With a single `*` as a value, you can back up all the databases of the DBMS.
 |
 
 |--include-metadata=none\|all\|users\|roles
-|Include metadata in file. Can't be used for backing system database.
-- roles - commands to create the roles and privileges (for both database and graph) that affect the use of the database
-- users - commands to create the users that can use the database and their role assignments
-- all - include roles and users
-- none - don't include any metadata
+|Include metadata in the file. This cannot be used for backing up the `system` database. Possible values are:
+
+- `roles` - include commands to create the roles and privileges (for both database and graph) that affect the use of the database.
+- `users` - include commands to create the users that can use the database and their role assignments.
+- `all` - include both `roles` and `users`.
+- `none` - does not include any metadata.
+[NOTE]
+`roles` and `users` that do not have database-related privileges are not included in the backup (e.g. those with only DBMS or no privileges). It is recommended to use `SHOW USERS` and `SHOW ROLES` to get the complete list of users and roles in these situations.
 |all
 
 |--inspect-path=<path>