Update docs

README.md

@@ -275,6 +275,7 @@ See more exporting options in the [Exporting Documentation](docs/exporting.md)
 --out-file    Filename for screenshot or PDF export
 --width       Width in pixels
 --height      Height in pixels
+--webpack     Path to webpack config file
 ```
 
 ## Docs

docs/advanced.md

@@ -95,6 +95,21 @@ Then, point the mdx-deck CLI comment in your `package.json` to the `deck.js` fil
 }
 ```
 
+## Custom webpack config
+
+Webpack configuration files named `webpack.config.js` will automatically be merged with the built-in configuration, using [webpack-merge](https://github.com/survivejs/webpack-merge). To use a custom filename, pass the file path to the `--webpack` flag.
+
+```js
+// webpack.config.js example
+module.exports = {
+  module: {
+    rules: [
+      { test: /\.svg$/, loader: 'react-svg-loader' }
+    ]
+  }
+}
+```
+
 ## Custom build setups
 
 The core mdx-deck components can also be used in any React application,