Add code splitting example / section

[basarat]

tsconfig needs module specification:

        "moduleResolution": "node",
        "module": "esnext",

webpack.config.js needs chunkFilename specificaiton:

    output: {
        path: path.join(__dirname, "dist"),
        filename: "[name].bundle.js",
        chunkFilename: "[name].chunk.js"
    },

More

You can also specify chunk names if you want to but I wouldn't:

await import(/* webpackChunkName: "foo" */ "./foo");