docs(scripts): drop the removed GENERATED_SKILL_ARTIFACTS from the check-doc-authoring control entry

The `why` record for `check-doc-authoring.mjs` in the ratchet-remedy-authority
control corpus named four declarations. `GENERATED_SKILL_ARTIFACTS` — the
by-path exemption for the generated `references/_index.md` /
`references/react-blocks.md` artifacts — was removed from the tree when its
sources stopped carrying projected issue ids, so the record's only surviving
mention of it was this prose string.

Drop that one name and move the conjunction (`A, B, C and D` -> `A, B and C`).
`ROOTS`, `SKIP_PATHS` and `SKIP_FILES` are all still declared and used in
`scripts/check-doc-authoring.mjs`, so the rest of the sentence stands. The
entry's closing line, about the per-passage allowlist, is left byte-identical.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UjM2ia8Av1v5NqfqQEQmC6

Author: claude

scripts/check-ratchet-remedy-authority.mjs

@@ -712,7 +712,7 @@ const CONTROL = {
   },
   'check-doc-authoring.mjs': {
     expect: 'excluded',
-    why: 'Carries no ratchet at all. ROOTS, SKIP_PATHS, SKIP_FILES and GENERATED_SKILL_ARTIFACTS are declarations of what the two corpus rules read and what is generated rather than authored; each is path-scoped, and none is offered to the author as something to widen. Its published-catalog id rule reached this corpus by first shipping a per-passage allowlist and being turned red here for offering it — maintainer ruling 2026-08-25 replaced that passage with a placeholder and removed the list. If this flips, that list came back.',
+    why: 'Carries no ratchet at all. ROOTS, SKIP_PATHS and SKIP_FILES are declarations of what the two corpus rules read and what is generated rather than authored; each is path-scoped, and none is offered to the author as something to widen. Its published-catalog id rule reached this corpus by first shipping a per-passage allowlist and being turned red here for offering it — maintainer ruling 2026-08-25 replaced that passage with a placeholder and removed the list. If this flips, that list came back.',
   },
   'check-error-code-casing.mjs': {
     expect: 'excluded',