Added some doc.

The *client* container provides the following command line tools:

- **vos_data**: launches a job to automatically store data provided by the user on a given storage point (hot or cold)

- **vos_group**: allows to add/list/remove users/groups to/from 'group_read' and/or 'group_write' of a VOSpace node and its child nodes (if any)

- **vos_import**: imports VOSpace nodes on the file catalog for data already stored on a given storage point

- **vos_job**: provides information about jobs

- **vos_storage**: allows to add/list/remove storage points.

3. You can obtain some info about the jobs by searching them on the following queues:

   - for write operations the queues are *write_pending*, *write_ready* and *write_terminated*

   - for read operations the queues are *read_pending*, *read_ready* and *read_terminated*

   - for import operations the queues are *import_ready* and *import_terminated*

   - for group operations the queues are *group_rw_ready* and *group_rw_terminated*

4. Some of the messages sent by the VOSpace REST APIs are handled by the following queues:

   - for starting async recalls the queue is *start_job_queue*

   - for getting info about job status the queue is *poll_job_queue*

5. The messages sent by the user command line tools are handled by the following queues:

   - for vos_data the queue is *data_queue*

   - for vos_group the queue is *group_queue*

   - for vos_import the queue is *import_queue*

   - for vos_job the queue is *job_queue*

   - for vos_storage the queue is *storage_queue*

```

redis:6379> lrange write_ready 0 5

```

By default, [AOF persistence](https://redis.io/topics/persistence) is enabled.

You can see the content of the AOF file with:

```

cat /data/appendonly.aof

```

#### File catalog