Provide link to bottlerocket for bare metal deprecation notice

[jaradtke-aws]

Issue #, if available: Provide link to bottlerocket for bare metal deprecation notice

@csplinter posted that bottlerocket is being deprecated as a supported method for bare metal as of EKS-A v0.19 (2024-02-29) The EKS-A documentation should also reflect that change. Bottlerocket is still viable for previous versions which are still supported, therefore references to bottlerocket and bare metal should not yet be removed - and instead just provide guidance for the change.

Description of changes: Provide a link to the github issue #7754 to guide the reader

Testing (if applicable):

Documentation added/planned (if applicable):

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