docs(readme): beautify regular expression (#38)

Author: azat-io

README.md

@@ -27,7 +27,7 @@ module.exports = {
 		new CompressionPlugin({
 			asset: "[path].gz[query]",
 			algorithm: "gzip",
-			test: /\.js$|\.html$/,
+			test: /\.(js|html)$/,
 			threshold: 10240,
 			minRatio: 0.8
 		})
@@ -93,4 +93,4 @@ Option Arguments for Zopfli (see [node-zopfli](https://github.com/pierreingleber
 [deps-url]: https://david-dm.org/webpack-contrib/webpack-loader-seed
 
 [chat]: https://img.shields.io/badge/gitter-webpack%2Fwebpack-brightgreen.svg
-[chat-url]: https://gitter.im/webpack/webpack
+[chat-url]: https://gitter.im/webpack/webpack