Adaptive auth section

[pankajtaneja5]

This PR introduces a new section on Adaptive or Risk-Based Authentication to the Multifactor Authentication Cheat Sheet. It explains how contextual signals (such as location, device fingerprint, and behavior) can be used to dynamically trigger additional authentication steps, improving both usability and security.

The section also includes a practical example to guide developers in implementing risk-based authentication flows.

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[szh]

This is a super important addition. Just needs a markdown lint fix:

cheatsheets/Multifactor_Authentication_Cheat_Sheet.md:433 MD032/blanks-around-lists Lists should be surrounded by blank lines [Context: "- Prompt for an additional fac..."]

[pankajtaneja5]

@szh Thanks! I’ve fixed the MD032 issue by adding the required blank line before the list.

[szh]

LGTM!

[pankajtaneja5]

Thank you for the review and approval! Could a maintainer please help merge this when ready? 🙏

[szh]

We just need another review from a maintainer. @jmanico @mackowski ?