Fix typo in USING_ADVANCED.md

[EdwardHoward]

Marked version:

Markdown flavor: Markdown.pl|CommonMark|GitHub Flavored Markdown|n/a

Description

• Fixes typo in USING_ADVANCED.md

Contributor

• Test(s) exist to ensure functionality and minimize regression (if no tests added, list tests covering this PR); or,
• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

Committer

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• Draft GitHub release notes have been updated.
• CI is green (no forced merge required).
• Merge PR

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[styfle]

Thanks!