fix: correct nested config recommendation

lib/manager/npm/extract/index.js

@@ -24,7 +24,7 @@ async function extractDependencies(content, packageFile, config) {
     const error = new Error('config-validation');
     error.configFile = packageFile;
     error.validationError =
-      'Nested package.json must not contain renovate configuration. Please use pathRules in your main config instead.';
+      'Nested package.json must not contain renovate configuration. Please use `packageRules` with `paths` in your main config instead.';
     throw error;
   }
   const packageJsonName = packageJson.name;