Reference to Azure Security Benchmark

[BernieWhite]

Some rules specifically check security controls defined in Azure Security Benchmark.

ASB provides a reference point to map Azure controls to other security standards, for example:

CIS Controls v8 ID(s)	NIST SP 800-53 r4 ID(s)	PCI-DSS ID(s) v3.2.1
5.4, 6.8	AC-2, AC-6	7.1, 7.2, 8.1

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Selected for development in issue #1610