Adds doc for default node identifier

[cosh]

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[prmerger-automator]

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

[learn-build-service-prod]

Learn Build status updates of commit 1f7852b:

✅ Validation status: passed

File	Status	Preview URL	Details
data-explorer/kusto/query/make-graph-operator.md	✅Succeeded

For more details, please refer to the build report.

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[prmerger-automator]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.

[ShannonLeavitt]

Hi @cosh

Microsoft authors and contributors need to make content contributions through the private repository so the content can be staged and validated by the current validation rules.

After you make your changes in the private repo, review the articles on staging, and fix any validation issues, you can add the sign-off comment to let PR reviewers know that the updates are ready to be merged.

Read about authors working in the public repo for more information.

If you need help getting set up to work in the private repo, see Get started contributing to the Microsoft Learn platform.

We'll close this PR. Thank you.