docs: remove public-release guard false positive from handoff documentation

[CasterlyGit]

Outcome

Make the public handoff documentation pass the repository's release/privacy guard without changing the documented feature or adding personal information.

Evidence

codex-public-guard currently reports handoff/README.md because it matches a generic guard term used for session-continuity prose. The file contains no personal career material, but the baseline finding blocks otherwise verified public documentation and test pull requests.

Acceptance criteria

• Rewrite only the affected generic wording while preserving the documented behavior.
• codex-public-guard <repo> passes from the default branch after the change.
• No behavioral, metadata, visibility, or ownership change.