Don't ask to install webpack for using Styleguidist (#2656)

* Don't ask to install webpack for using Styleguidist

* Update README.md

Author: gaearon

packages/react-scripts/template/README.md

@@ -1470,10 +1470,10 @@ Learn more about React Storybook:
 
 Styleguidist combines of a style guide, where all your components are presented on a single page with their props documentation and usage examples, with an environment for developing components in isolation, similar to Storybook. In Styleguidist you write examples in Markdown, where each code snippet is rendered as a live editable playground.
 
-First install Styleguidist and peer dependencies from npm:
+First, install Styleguidist:
 
 ```sh
-npm install --save-dev react-styleguidist webpack
+npm install --save-dev react-styleguidist
 ```
 
 Then, add these scripts to your `package.json`: