Adds Child Theme command to npm run list to create new child theme from _dsgnsystm parent theme.

_dsgnsystm/package.json

@@ -41,6 +41,6 @@
     "build:print": "node-sass print.scss print.css --output-style expanded --indent-type tab --indent-width 1 && postcss -r print.css",
     "build": "run-p \"build:*\"",
     "watch": "chokidar \"**/*.scss\" -c \"npm run build\" --initial",
-    "child": "sh ../build-tools/build-child-theme.sh"
+    "child-theme": "sh ../theme-dev-utils/build-child-theme.sh"
   }
 }