[Crusoe] Minor edits

[peterschmidt85]

Note

Updates Crusoe README wording and references without code changes.

• Rename Kubernetes to Crusoe Managed Kubernetes (with anchor), update all references and tabs accordingly
• Add mentions of NVIDIA and AMD GPU support for both Kubernetes and VMs; refine VM section to highlight SSH fleets usage
• Adjust NCCL test instructions and the privileged note for Kubernetes; minor link/title tweaks and copyedits throughout

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