fix(kyberforge): apply cross-skill audit findings to skill factory trio

- skill-audit: remove contradictory skip clause in Step 2 (binary only)
- skill-improve: drop redundant "Fix the root" heading; keep specific directive
- skill-write: add section-rename guidance to body discipline step
- template SKILL.md: make Instructions heading an explicit FILL IN placeholder
- template README.md: remove "Invoke via your agent tool:" prefix to match convention

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

plugins/kyberforge/skills/skill-write/assets/templates/README.md

@@ -15,8 +15,6 @@
 
 ## Usage
 
-Invoke via your agent tool:
-
 ```
 /SKILL_NAME
 ```