Use better volume examples

[owainlewis]

Currently the examples used for volumes use a hostpath volume. This has, from experience, led to some confusion since it generally won't work without modification of the example. We would be better off using a different example for volumes.

[bweston92]

Can we have an example for GKE too, just upgraded a node pool and lost everything as I didn't realise it was using host path aha

[owainlewis]

@bweston92 yes we'll update the examples to work on any K8s cluster. That would make it easier for users looking to get started quickly.