Add information to use styleguide extension (#252)

* Add information to use styleguide extension

Resolves: #250

* Update UseStyleguide.rst

Co-authored-by: Tom Warwick <[email protected]>

Documentation/Index.rst

@@ -55,6 +55,7 @@ On these pages you will learn how to become a TYPO3 Core contributor.
    Setup/Prerequisites
    Setup/SetupTypo3
    Setup/Git/Index
+   Setup/UseStyleguide
    Setup/SetupIde
 
 .. toctree::

Documentation/Setup/UseStyleguide.rst

@@ -0,0 +1,45 @@
+.. include:: /Includes.rst.txt
+
+.. highlight:: bash
+
+.. _use-styleguide:
+
+==================
+Use EXT:styleguide
+==================
+
+It is recommended to use the styleguide extension to auto generate several
+example pages which can be used for testing the frontend and backend of TYPO3.
+
+The typo3/cms-styleguide extension is part of the TYPO3 core repository.
+It used mostly to showcase TCA / FormEngine features but has since evolved
+to provide additional features.
+
+The styleguide extension can create pages within the TYPO3 site, specifically:
+
+*  The "Styleguide TCA demo" will create several pages showcasing TCA features,
+   including examples for common column types.
+*  The "Styleguide Frontend" uses a custom TypoScript template provided by
+   the styleguide extension and creates pages which can be viewed
+   in the frontend.
+
+Setup
+=====
+
+.. rst-class:: bignums-xxl
+
+1. Activate the styleguide extension in the extension manager
+2. Click on :guilabel:`?` in the top bar
+3. Click on the :guilabel:`Styleguide` menu item
+
+   The Styleguide overview appears.
+
+4. Click on :guilabel:`TCA / Records / Frontend`
+5. Create pages
+
+   Click the buttons:
+
+   *  :guilabel:`Create styleguide page tree with data`
+   *  :guilabel:`Create styleguide frontend`
+
+The pages will now be created. Wait a moment until a flash message appears.