docs: Add yarn to README and hint to react-styleguidist

Author: danez

README.md

@@ -9,14 +9,22 @@ It provides a default implementation for React components defined via
 (stateless components). These component definitions must follow certain
 guidelines in order to be analyzable (see below for more info).
 
+> react-docgen is a low level tool to extract information about react components. If you are searching for a more high level tool try https://github.com/styleguidist/react-styleguidist which comes with a complete styleguide and is build on top of react-docgen.
+
 ## Install
 
-Install the module directly from npm:
+Install the module with yarn or npm:
+
+```
+yarn add react-docgen --dev
+```
 
 ```
-npm install -g react-docgen
+npm install react-docgen
 ```
 
+
+
 ## CLI
 
 Installing the module adds a `react-docgen` executable which allows you to convert