Simplify eslint command

Author: wojtekmaj

package.json

@@ -12,7 +12,7 @@
     "build-umd": "BABEL_ENV=production-umd babel src -d dist/umd --ignore \"**/*.spec.js\"",
     "clean": "rimraf dist",
     "jest": "jest",
-    "lint": "eslint src/ --ext .jsx,.js",
+    "lint": "eslint src",
     "postinstall": "husky install",
     "prepack": "yarn clean && yarn build",
     "prettier": "prettier --check . --cache",