Add timeline for breaking changes in raw-menu-anchor-close-order

[davidhicks980]

Description of what this PR is changing or adding, and why:
Adds a timeline for breaking changes in raw-menu-anchor-close-order. I didn't fill in the stable version yet -- should I?

PRs or commits this PR depends on (if any):
flutter/flutter#182357

@dkwingsmt

Presubmit checklist

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• This PR uses semantic line breaks
  of 80 characters or fewer.

[gemini-code-assist]

Code Review

This pull request adds a Timeline section to the breaking changes documentation for RawMenuAnchor. The review feedback suggests replacing the HTML line break tag with a Markdown list to adhere to style guidelines and improve readability.

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit e695cf9):

https://flutter-docs-prod--pr13287-timeline-bm2lqf1r.web.app

[parlough]

Thanks for adding this!