rename sample config and update instructions a bit

Author: moda-schneij

source/_app/samples/webpack.app.scss.js source/_app/samples/webpack.app.jssource/_app/samples/webpack.app.scss.js renamed to source/_app/samples/webpack.app.js

@@ -1,9 +1,9 @@
 /**
- * NOTE: THIS IS A SAMPLE, THIS SHOULD BE webpack.app.js one level higher to be used in your project.
+ * NOTE: THIS IS A SAMPLE. Modify webpack.app.js one level higher to be used in your project.
  * Add new dependencies like so:
- * "yarn add autoprefixer import-glob-loader css-loader node-sass postcss-loader postcss-flexbugs-fixes MiniCssExtractPlugin sass-loader style-loader --dev"
+ * "yarn add autoprefixer import-glob-loader css-loader node-sass postcss-loader postcss-flexbugs-fixes mini-css-extract-plugin sass-loader style-loader --dev"
  * or
- * "npm install autoprefixer import-glob-loader css-loader node-sass postcss-loader postcss-flexbugs-fixes MiniCssExtractPlugin sass-loader style-loader --save-dev"
+ * "npm install autoprefixer import-glob-loader css-loader node-sass postcss-loader postcss-flexbugs-fixes mini-css-extract-plugin sass-loader style-loader --save-dev"
  */