basic toc support

Rules

@@ -89,7 +89,7 @@ compile '*' do
     case @item[:extension]
     when "mkd" # normal pages
       filter :erb
-      filter :kramdown
+      filter :kramdown, :toc_levels => [1,2]
       filter :colorize_syntax, :default_colorizer => :pygmentize
     when "org" # org-mode pages
       filter :org

lib/default.rb

@@ -25,6 +25,10 @@ def route_unchanged
   item.identifier.chop + '.' + item[:extension]
 end
 
+def toc
+  "- ToC\n{:toc}"
+end
+
 class Nanoc3::Site
   # only articles that actually get printed
   attr_reader :printed_items