IPA Docs lack get_deploy_steps and get_service_steps details

The IPA hardware manager docs in the agent lack details on how to add deploy and service steps to be returned to ironic.

We should fix this and include examples, since many of these things are very similar, and you may have cleaning steps which need to be available during deploy, and custom deploy steps available during service operations.

https://docs.openstack.org/ironic-python-agent/latest/contributor/hardware_managers.html