Clarify the details of "Amazon EKS optimized Kubecost bundle"

[guessi]

Issue #, if available:

Description of changes:

• Correct outdated links.
• Correct the terms of Kubecost and Amazon EKS optimized Kubecost custom bundle.
• Aligned the wording Unlimited clusters up to 250 cores with https://www.kubecost.com/pricing/ page.
• Update command to make it compatible with both v1 and v2.
• Update requirements for running kubecost v2.
• Unify the style of the flags -n and --namespace.
• Unify the wording of "Amazon EKS optimized Kubecost bundle".

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