Update Set-DlpComplianceRule.md

[aamalhot]

update UnscannableDocumentExtensionIs

[opbld30]

Docs Build status updates of commit 6b5fc0c:

✅ Validation status: passed

File	Status	Preview URL	Details
exchange/exchange-ps/exchange/Set-DlpComplianceRule.md	✅Succeeded	View (exchange-ps)

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