docs(changelog): Fleet library source column, onboarding affordance, table heights

[indykish]

Paired with agentsfleet #709.

Changes

• changelog.mdx — a Sep 23 <Update> covering the Fleet library source column, the matched columns across both tables, the Getting started button, and the three table-height fixes.
• fleets/library.mdx:109 — corrected. It named the workspace sidebar entry Library; that entry now reads Fleet library, matching the platform one.

Verified

make documentation check passed on commit: Ran 22 tests ... OK / Documentation check passed.

🤖 Generated with Claude Code

Confidence Score: 5/5

The documentation changes appear safe to merge, with the previously conflicting save guidance now resolved.

Findings

1.  Conflicting save guidance ▶

Fix with agent prompt

### Issue 1
changelog.mdx:undefined-30
The new release note says that after a genuine concurrent edit, saving again overwrites the server copy. However, `fleets/overview.mdx` says stale saves are refused and users must reload and reapply their changes, and `api-reference/error-codes.mdx` gives the same recovery instructions. This contradiction leaves users unsure whether a second save will intentionally discard another operator's update. If overwrite-on-second-save is the new behavior, update the durable fleet-editing and error-code documentation alongside this entry.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

This PR documents recent Fleet library and dashboard improvements, corrects the workspace navigation label, and clarifies concurrent fleet-source editing behavior.

• Adds a Sep 23 changelog entry covering source provenance, aligned library tables, onboarding improvements, and table-height fixes.
• Renames the documented workspace sidebar entry from Library to Fleet library.
• Distinguishes the dashboard’s reviewed overwrite flow from the API’s UZ-AGT-014 stale-write recovery flow.

_{Reviews (3) · Last reviewed commit: "docs(fleets): a stale source save reads ..."}