Clean up state-machine workflow: remove stale refs, fix numbering (#19784)

- Exclude shared/ from workflow discovery (for repos with shared imports)
- Remove tooling-check-repo-rules.md reference (belongs to the security
  scan workflow, not the diagram generator)
- Fix rule numbering gap (was 1,2,3,4,5 → now 1,2,3,4)
- Replace fsharp-specific 'repo-assist' example with generic placeholder

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: T-Gro