[examples/react-example] add missed css

examples/react-example/package.json

@@ -2,7 +2,8 @@
   "private": true,
   "name": "uppy-react-example",
   "scripts": {
-    "start": "budo main.js:bundle.js -- -r react:react -r react-dom:react-dom -t babelify -g aliasify"
+    "css": "cp ../../dist/uppy.min.css .",
+    "start": "npm run css && budo main.js:bundle.js -- -r react:react -r react-dom:react-dom -t babelify -g aliasify"
   },
   "aliasify": "./aliasify.js",
   "dependencies": {