Fix isse of sourceMapLoader looking at node_modules

packages/react-docs/webpack.config.js

@@ -24,6 +24,10 @@ module.exports = {
             {
                 test: /\.js$/,
                 loader: 'source-map-loader',
+                exclude: [
+                    // instead of /\/node_modules\//
+                    path.join(process.cwd(), 'node_modules'),
+                ],
             },
             {
                 test: /\.tsx?$/,