Fix typo in takerAsset value in Overview.md

[dw61]

Note

Low Risk
Documentation-only change correcting an example value; no runtime or contract logic is affected.

Overview
Fixes a typo in docs/Overview.md where the Scenario 2 (MINT) taker order example incorrectly listed takerAsset as A''; it now correctly uses A' to match the narrative and asset definitions.

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