Improve C4324 warning reference

[Rageking8]

• Add "Remarks" and "Example" headings
• Change "structname" in warning message to "type" as C4324 also applies to class and union
• Add some details about "class/struct/union" and alignas in the remarks
• Improve example:
  • Remove superfluous main function and add /c flag
  • Prefer standard alignas over __declspec(align)
  • Extend the example with an empty struct and okay case
• Update metadata

[prmerger-automator]

@Rageking8 : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[v-dirichards]

@TylerMSFT

Can you review the proposed changes?

Important: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team

[learn-build-service-prod]

Learn Build status updates of commit 683a635:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/error-messages/compiler-warnings/compiler-warning-level-4-c4324.md	✅Succeeded
docs/error-messages/compiler-warnings/compiler-warnings-c4200-through-c4399.md	✅Succeeded

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PRMerger Results

Issue	Description
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