Drop redundant docs/ prefix in sp-stack fallback path

The anchor clause already establishes ${CLAUDE_PLUGIN_ROOT}/docs/, so the
first traversal element is README.md, not docs/README.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/skills/sp-stack/SKILL.md

@@ -38,7 +38,7 @@ and a booking calendar"*.
    - **Manifest hit** → take `primary` + `supporting`; open its `example_doc` under
      `${CLAUDE_PLUGIN_ROOT}/docs/` and read the quick-start block verbatim.
    - **Manifest miss** → fall back to the `sp` docs-traversal under
-     `${CLAUDE_PLUGIN_ROOT}/docs/`: `docs/README.md` → `<category>/README.md` →
+     `${CLAUDE_PLUGIN_ROOT}/docs/`: `README.md` → `<category>/README.md` →
      `<subcategory>/README.md` → package `README.md`, ranking turnkey `api-plugin-*` /
      engine packages above low-level primitives.