chore(package): update html-webpack-plugin to version 4.0.1

Closes #178

Author: greenkeeper[bot]

examples/react-hot-loader/package.json

@@ -12,7 +12,7 @@
     "babel-preset-env": "^1.6.1",
     "babel-preset-react": "^6.24.1",
     "flow-bin": "^0.110.0",
-    "html-webpack-plugin": "^3.2.0",
+    "html-webpack-plugin": "^4.0.1",
     "webpack": "^4.21.0",
     "webpack-cli": "^3.1.2",
     "webpack-dev-server": "^3.1.9"