Добавил npm-скрипт оптимизации картинок

package.json

@@ -15,6 +15,7 @@
     "start": "gulp",
     "deploy": "cross-env NODE_ENV=production ./node_modules/.bin/gulp build && cross-env ./node_modules/.bin/gulp deploy",
     "build": "cross-env NODE_ENV=production npm start build",
+    "img-opt": "cross-env folder=src/img npm start img:opt",
     "lint-staged": "lint-staged",
     "precommit": "lint-staged && gulp test:pug"
   },