Add NFS support

[gautierdag]

Given we now have an NFS partition. This allows us to use it by passing the following:

    job = KubernetesJob(
       ...
        volume_mounts={
            "nfs": {"mountPath": "/nfs", "server": "10.24.1.255", "path": "/"}
        },
    )

Then from within the pod we can access it at /nfs/...

[AntreasAntoniou]

Can you add an example in the README.md? Then we can merge this! :)

[gautierdag]

@AntreasAntoniou done, let me know if you want more!

[AntreasAntoniou]

Excellent! Merging.