docs(guides): Added publicPath to output (#2420)

Without this i was finding that webpack wasn't able to find the file which was being dynamically imported which was also reported here webpack/webpack#7502.

Adding this allowed my example to work as expected - makes extra network request to and executes the file.

Author: qasimalyas

src/content/guides/code-splitting.md

@@ -184,6 +184,7 @@ __webpack.config.js__
     output: {
       filename: '[name].bundle.js',
 +     chunkFilename: '[name].bundle.js',
+      publicPath: 'dist/',
       path: path.resolve(__dirname, 'dist'),
     },
 -   optimization: {