(GH-156) Clarifiy glossary for DSCv3/PSDSC

[michaeltlombardi]

PR Summary

This change further clarifies the distinction and terminology to reduce confusion about PowerShell Desired State Configuration in DSCv3.

PR Checklist

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

[learn-build-service-prod]

Learn Build status updates of commit 4c29e17:

✅ Validation status: passed

File	Status	Preview URL	Details
.vscode/cspell/dsc/dictionaries/dsc-terms.txt	✅Succeeded
.vscode/styles/Vocab/PowerShell-Docs/accept.txt	✅Succeeded
dsc/docs-conceptual/dsc-3.0/concepts/resources.md	✅Succeeded	View (dsc-3.0)
dsc/docs-conceptual/dsc-3.0/glossary.md	✅Succeeded	View (dsc-3.0)
dsc/docs-conceptual/dsc-3.0/overview.md	✅Succeeded	View (dsc-3.0)

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