README.md in gollum-descendant_tree-0.0.5 vs README.md in gollum-descendant_tree-0.0.6

@@ -14,9 +14,28 @@
 
 Or install it yourself as:
 
     $ gem install gollum-descendant_tree
 
+## Setup
+
+Then, add to your Gollum app's `config.ru`:
+
+    require 'gollum/descendant_tree'
+
+Create a custom markup class if you don't already have one, or just `include Gollum::DescendantTree` in your existing class.
+
+    # lib/gollum/my_markup.rb
+    class MyMarkup < Gollum::Markup
+      include Gollum::DescendantTree
+    end
+
+Finally, in `config.ru`, tell Gollum to use your class instead of its default one.
+
+    Precious::App.set(:wiki_options, {
+      :markup_classes => { :markdown => MyMarkup }
+    })
+
 ## Usage
 
 Simply add `[[_TREE_]]` to any page of your wiki to add an unordered list of descendants to the page. If you're using custom css, you can target `ul.tree` for styling the list.
 
 ## Automated Tests