add SourceMaps configuration in readme

Author: vallemar

README.md

@@ -23,6 +23,17 @@ and choose NativeScript debug environment.
 
 ### Debug your NativeScript application
 
+#### SourceMaps configuration
+Add in `webpack.config.js` file the next configuration.
+
+```js
+webpack.chainWebpack(config => {
+    config.output.devtoolNamespace('app')
+})
+```
+
+#### Start debug
+
 To start the application with attached debugger, choose one of the launch configurations from the drop-down list and then click the start button.
 
 ![Launch settings](https://raw.githubusercontent.com/NativeScript/nativescript-vscode-extension/master/images/screenshots/nativescript-launch-configurations.png)