Privacy: Expand Compose, revise Copilot

[majenny]

Rendered article section for review:

• Microsoft Edge Privacy Whitepaper > Compose
  • https://review.learn.microsoft.com/microsoft-edge/privacy-whitepaper/index?branch=pr-en-us-3206#compose
  • Before/Live
• Microsoft Edge Privacy Whitepaper > Copilot in Microsoft Edge sidebar
  • https://review.learn.microsoft.com/microsoft-edge/privacy-whitepaper/index?branch=pr-en-us-3206#copilot-in-microsoft-edge-sidebar
  • Before/Live

AB#51951149

[majenny]

This PR LGTM, thanks all for reviewing!

[learn-build-service-prod[bot]]

Learn Build status updates of commit 25f8f70:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
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microsoft-edge/privacy-whitepaper/index-images/summarize-content.png	:white_check_mark:Succeeded	n/a (file deleted or renamed)
microsoft-edge/privacy-whitepaper/index.md	:white_check_mark:Succeeded	View

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