fix(package): update browser file name

Author: jaebradley

package.json

@@ -4,7 +4,7 @@
   "description": "Example React Component for npm Publication using Rollup",
   "main": "build/index.cjs.js",
   "module": "build/index.esm.js",
-  "browser": "build/index.umd.js",
+  "browser": "build/index.js",
   "files": [
     "build"
   ],