Docs content model reorg

[suearkinunity]

Description

Redone the TOC based on the plan from Ben and Siobhan.

Testing status & QA

Docs only

Overall Product Risks

None - docs only

Comments to reviewers

ZIP and comments provided on the team Slack channel

Checklist

Before review:

• Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • JIRA ticket linked, example (case %%). If it is a private issue, just add the case ID without a link.
  • Jira port for the next release set as "Resolved".
• Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
  • Performance tests.
  • Integration tests.
• Docs for new/changed API's.
  • Xmldoc cross references are set correctly.
  • Added explanation how the API works.
  • Usage code examples added.
  • The manual is updated, if needed.

During merge:

• Commit message for squash-merge is prefixed with one of the list:
  • NEW: ___.
  • FIX: ___.
  • DOCS: ___.
  • CHANGE: ___.
  • RELEASE: 1.1.0-preview.3.

[u-pr]

⚠️ Review skipped — this PR is too large to process.

The diff contains approximately 396,848 tokens (~1,190,545 characters), which exceeds the maximum limit of 150,000 tokens.

Please consider splitting this PR into smaller, focused changes.

_{🤖 Helpful? 👍/👎}

[cla-assistant-unity]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
3 out of 4 committers have signed the CLA.

✅ siobhan-unity
✅ duckets
✅ jo-unity
❌ suearkinunity
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