helm step, push action, kube_context is required

[jor-rit]

For a helm step, in the examples and documentation a action: push is given without passing a kube_context argument.
But kube_context is marked as 'required' in the docs and in the yaml/json schema.
So the step fails with a validation error.

So either kube_context is made conditional with some subschemas or the examples need to be changed (though a kubernetes cluster isn't needed to only push a chart).

[kostis-codefresh]

Thanks for catching this. We will work on this ASAP