Added new section on layer positions

[stevemunk]

PR Review Team: This PR is part of an established workflow, please merge when I sign off. Thanks.

[prmerger-automator]

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[learn-build-service-prod]

Learn Build status updates of commit 16c1462:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/azure-maps/media/power-bi-visual/layer-position.png	✅Succeeded
articles/azure-maps/power-bi-visual-understanding-layers.md	✅Succeeded

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[prmerger-automator]

PRMerger Results

Issue	Description
Added File(s)	This PR contains added files. New files require human review.
Image File	This PR added or updated an image file(s).

[v-dirichards]

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