fix(document-release): one canonical spawned contract, downstream notes are pointers

The diff-selected LLM-judge eval scored the skill's clarity 3 (threshold
4, main scores 4): the spawned-session rules read as three separately-
framed rule sets (contract paragraph, Step 8.4d note, Codex-review skip).
The contract paragraph now declares itself the single source of spawned
behavior and the two downstream notes reference it instead of restating
rationale. The pointer avoids naming the Codex section verbatim so the
codex-host render (which strips that section) keeps its negative pin.
Judge re-scored 4/5/4 across repeated samples after the change.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

document-release/SKILL.md

@@ -456,9 +456,10 @@ the AskUserQuestion Format spawned rule: auto-choose the RECOMMENDED option, rec
 in your completion report, and continue — never call AskUserQuestion, never render a prose
 decision brief, never end your response waiting for an answer. The NEVER-do invariants below do
 not relax: when a gate's recommended option would rewrite CHANGELOG content or change VERSION,
-take that gate's Skip / leave-as-is option instead and record why (Step 8 carries the explicit
-spawned note). If the dispatch prompt narrows scope further (e.g. /ship's docs-sync-only guard),
-the prompt's restrictions win.
+take that gate's Skip / leave-as-is option instead and record why. This paragraph is the single
+source of spawned behavior — the spawned notes downstream (Step 8's VERSION gate, the
+cross-model doc-review pass) are pointers back to it, not separate rules. If the dispatch
+prompt narrows scope further (e.g. /ship's docs-sync-only guard), the prompt's restrictions win.
 
 **Only stop for:**
 - Risky/questionable doc changes (narrative, philosophy, security, removals, large rewrites)