Update README.md to add Amber and Crystal from llm360

[TianhuaTao]

Update README.md to add Amber and Crystal from llm360 as baselines.

I am using aggregated_centered_results as EXTENDED and aggregated_results as CORE.

[achalddave]

Thanks! Two notes:

• CORE should actually be low_variance_datasets_centered
• It looks like you've copied Falcon an extra time here.

Could you please update these two, and also update the CORE on the two HF repos where you made a PR? Thank you!