K8S: Add migration tutorial (scaleway#3973)

* docs(k8s): add tutorial kubernetes migration

* docs(k8s): migration tutorial

* Apply suggestions from code review

Co-authored-by: Rowena Jones <[email protected]>

* Apply suggestions from code review

Co-authored-by: nerda-codes <[email protected]>

* Update tutorials/migrating-from-another-managed-kubernetes-service-to-scaleway-kapsule/index.mdx

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Co-authored-by: Rowena Jones <[email protected]>
Co-authored-by: nerda-codes <[email protected]>

Author: 3 people