Added simple demonstration of has_many :through

railties/guides/source/association_basics.textile

@@ -165,6 +165,12 @@ class Paragraph < ActiveRecord::Base
 end
 </ruby>
 
+With +:through => :sections+ specified, Rails will now understand:
+
+<ruby>
+  @document.paragraphs
+</ruby>
+
 h4. The +has_one :through+ Association
 
 A +has_one :through+ association sets up a one-to-one connection with another model. This association indicates that the declaring model can be matched with one instance of another model by proceeding _through_ a third model. For example, if each supplier has one account, and each account is associated with one account history, then the customer model could look like this: