docs(skills): fix nix rule discovery path

src/skills/nix-style/SKILL.md

@@ -10,10 +10,10 @@ Use this skill as the source of truth for repository Nix conventions.
 ## Load rules
 
 Read every Markdown file under [`rules/`](rules/) before applying this skill.
-Use this command from the skill directory when file names are unknown:
+Discover rule files from the skill source:
 
 ```bash
-find rules -type f -name '*.md' -print | sort
+find src/skills/nix-style/rules -type f -name '*.md' -print | sort
 ```
 
 Finish when all discovered rule files have been read.