Clean up colors documentation to be more clear about MD2/MD3

[manojleaton]

Fixes #BLUI-5762 .

Changes proposed in this Pull Request:

• Demo feedback changes

Screenshots / Screen Recording (if applicable)

To Test:

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Any specific feedback you are looking for?

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[github-actions[bot]]

Visit the preview URL for this PR (updated for commit b177936):

https://blui-doc-it--pr745-feature-5762-demo-fe-b37kugmn.web.app

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