docs(6205): the remaining services files state the reason, not the instance that taught it

The 1-2 hit tail: access, background, backup, backup_job, canonical_systems,
design_stylesheet, forge_connections, moment_actions, notes, notifications,
placement, planning, platforms, projects, record_batch, recurrence,
report_check, retrieval_review, rule_scope, rule_versions, scheduler,
shape_check, supersession, system_rulings, system_usage, text, trash,
verification, version_pinning.

Also corrected while reading:
- backup.py said restore step 16 fills the System map; step 15 does.
- version_pinning.py pointed at a design doc that is not in the repo.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/services/backup.py

@@ -2781,7 +2781,7 @@ async def _restore_v2(data: dict) -> dict:
             session.add(event)
             stats["rule_usage_events"] += 1
 
-        # And the System twin, after the Systems (step 16 fills their map).
+        # And the System twin, after the Systems (step 15 fills their map).
         for ev in data.get("system_usage_events", []):
             event = _build_system_usage_event(ev, maps)
             if event is None: