add pointer where to find "include static" (#615)

Documentation/Installation/Index.rst

@@ -9,7 +9,7 @@ Installation
 Follow the standard process of a TYPO3 installation (see :ref:`t3install:start`).
 After TYPO3 is running, we can continue installing the headless extension:
 
-#. **Install and activate the extension** with Composer `composer require friendsoftypo3/headless` (recommend),
+#. **Install and activate the extension** with Composer `composer require friendsoftypo3/headless` (recommended),
    or using the extension manager with key `headless`.
 
 #. **Create a new root page:** The page will provide our JSON API endpoint.
@@ -18,8 +18,8 @@ After TYPO3 is running, we can continue installing the headless extension:
       :alt: Root page for the API endpoint
       :class: with-shadow
 
-#. **Create a new root template:** Add headless to "Include static (from extensions)". After saving and displaying
-   the page, we can see already the JSON output.
+#. **Create a new root template:** Open the backend's menu entry *Site Management* > *TypoScript* (before v12: *Web* > *Template*). Add "`headless`" to "Include static (from extensions)". After saving and displaying
+   the page, we can see already the JSON output. 
 
 #. **Create a site configuration:** The site URL is needed as endpoint URL for the frontend.
    In TYPO3 v10 an autogenerated site configuration might exsist which we can rename and configure to our preferences.