(GH-233) Add `Import-DSCResource`

[michaeltlombardi]

PR Summary

Add missing Import-DSCResource statements to all configuration blocks in examples.

• Resolves #233
• Fixes AB#196403

PR Checklist

• [x] Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• [x] Summary: This PR's summary describes the scope and intent of the change.
• [x] Contributor's Guide: I have read the contributors guide.
• [x] Style: This PR adheres to the style guide.

[learn-build-service-prod[bot]]

Learn Build status updates of commit 25b03e0:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
dsc/docs-conceptual/dsc-1.1/reference/resources/packagemanagement/PackageManagementDscResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/packagemanagement/PackageManagementSourceDscResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/fileResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/packageResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/registryResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/serviceResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/serviceSetResource.md	:white_check_mark:Succeeded	View (dsc-1.1)
dsc/docs-conceptual/dsc-1.1/reference/resources/windows/windowsFeatureSetResource.md	:white_check_mark:Succeeded	View (dsc-1.1)

For more details, please refer to the build report.

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