Remove placeholder documentation

docs/user-guide/configuration.md

@@ -153,31 +153,19 @@ Lets you set the directory where the output HTML and other files are created.  T
 
 **default**: `'site'`
 
----
-
 **Note**: If you are using source code control you will normally want to ensure that your *build output* files are not commited into the repository, and only keep the *source* files under version control.  For example, if using `git` you might add the following line to your `.gitignore` file:
 
     site/
 
 If you're using another source code control you'll want to check its documentation on how to ignore specific directories.
 
----
 
-<!--
-## Extra build steps
 
-#### include_search
 
-TODO
 
-#### include_404
 
-TODO
 
-#### include_sitemap
 
-TODO
--->
 
 ## Preview controls