How to add an new disk to an exists bookkeeper node?

#### Expected behavior

When my pulsar cluster ledgerDirectories path is full,I want to increase ledgerDirectories capacity.How can I expand the storage capacity by increasing the existing node disks instead of increasing the number of nodes? Because I don't have more machines. Is there any document?

thank you very much.

#### Actual behavior

#### Steps to reproduce

#### System configuration
**Pulsar version**:2.8.0

Start by investigating how Pulsar 2.8.0 handles BookKeeper nodes and the ledgerDirectories path when storage is full. Done means documenting whether capacity can be expanded on an existing node and the supported procedure for users without additional machines.

Written by the indexing model from the issue text.