Please add nushell completion

[MrRulf]

What would you like to be added:
kubectl completion nushell

Why is this needed:
Nushell is amazing for working with kubernetes, exceeding every other shell i know. The only disadvantage is the lack of completion.

[k8s-ci-robot]

This issue is currently awaiting triage.

SIG CLI takes a lead on issue triage for this repo, but any Kubernetes member can accept issues by applying the triage/accepted label.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.