fix(skill-author): resolve audit findings from post-#8 review

- Remove implementation-focused sentence from description (was not user-intent
  language per agentskills.io spec)
- Move source_keys template comment under metadata: block to match Step 5's
  instruction; contradicted agents scaffolding before reading Step 5
- Add Step 6 to new-skill.sh next-steps (populate references/sources.md);
  renumber validate step to 7 — script was missing the sources step entirely

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/kyberforge/skills/skill-author/assets/templates/SKILL.md

@@ -28,14 +28,11 @@ description: >
 #   author: your-name
 #   version: "1.0"
 #   category: general
+#   source_keys:
+#     - source-slug-one
+#     - source-slug-two
 # Optional. Arbitrary key-value map. Common keys: author, version, category.
-# No restrictions on keys or values.
-
-# source_keys:
-#   - source-slug-one
-#   - source-slug-two
-# Optional. Populated when this skill was built from /research output.
-# Lists slugs from references/sources.md that informed this file.
+# source_keys: populated when built from /research output. Lists slugs from references/sources.md.
 # Also add source_keys to each references/*.md file that was informed by research.
 
 # allowed-tools: Bash Read Write