add docs for new config

packages/react-scripts/backpack-addons/README.md

@@ -14,7 +14,9 @@ Our react scripts fork includes a number of custom configuration items in order
 | **ssrExternals**            | The same as above `externals` except used for server side rendering only in **ssr.js**                                                                                                                                                                                                                                                                                                                                                        | **{}**                                                                                                                                          |
 | **enableAutomaticChunking** | Opts into automatic chunking of vender, common and app code.<br> When enabled the **splitChunks** plugin creates vender and common chunks which are split and when provided uses the `venderChunkRegex` to specify what is in each chunk.<br> When enabled **runtimeChunk** plugin creates a separate runtime chunk for projects to enable long term caching.                                                                                 | **false**                                                                                                                                       |
 | **vendorsChunkRegex**       | Regex for picking what goes into the vendors chunk. Requires enableAutomaticChunking to be enabled.<br> See [cacheGroups](https://webpack.js.org/plugins/split-chunks-plugin/#splitchunkscachegroups) docs for further details.                                                                                                                                                                                                               |                                                                                                                                                 |
-| **splitChunksConfig**       | Object, mapping to the [structure in the webpack docs](https://webpack.js.org/plugins/split-chunks-plugin/#optimizationsplitchunks).<br> Applied only if `enableAutomaticChunking` is false, ignores `vendorsChunkRegex` if defined.                                                                                                                                                                                                          |                                                                                                                                                 |
+| **splitChunksConfig**       | Object, mapping to the [structure in the webpack docs](https://webpack.js.org/plugins/split-chunks-plugin/#optimizationsplitchunks).<br> Applied only if `enableAutomaticChunking` is false, ignores `vendorsChunkRegex` if defined.                                                                                                                                                                                                          |
+| **enableBpkStylesChunk**       | Boolean, when enabled will create a single chunk for all Backpack CSS.                                                                                                                                                                                                          | false                                                                                                                                                |
+
 
 ## How to add new feature