docs: add safety warning to Array.from_buffers docstring

[avasis-ai]

Summary

Adds a .. warning:: directive to the Array.from_buffers docstring to explicitly inform callers that they are responsible for passing valid Arrow data matching the given type, and that passing invalid data may lead to crashes or undefined behavior.

This addresses the concern raised in the issue that users may not be aware of the safety implications of using this low-level API.

Closes #49717

[github-actions]

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