Replace backslash with forward slash for "C++/CLI"

[Rageking8]

Replace the only instance of "C++\CLI" with the correct "C++/CLI".

[prmerger-automator]

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

[learn-build-service-prod]

Learn Build status updates of commit 0140c18:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/dotnet/how-to-define-and-consume-classes-and-structs-cpp-cli.md	✅Succeeded

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[v-regandowner]

@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

[TylerMSFT]

Intriguing typo