docs:Missing sudo command

*Please describe the question or issue you're facing with "Mount MicroCeph backed Block Devices - MicroCeph documentation".*

There must be a sudo in the last command (sudo rbd pool init block_pool), otherwise, it will give an error as "rbd: couldn't connect to the cluster!".

Create a pool for RBD images:

$ sudo ceph osd pool create block_pool
pool 'block_pool' created

$ sudo ceph osd lspools
1 .mgr
2 block_pool

_**$ rbd pool init block_pool**_

There must be a sudo in the last command.
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*Reported from: https://canonical-microcloud.readthedocs-hosted.com/en/latest/microceph/tutorial/mount-block-device/*