Merge pull request #509 from gucki/master

fix bug in usage example of #unscoped

activerecord/lib/active_record/base.rb

@@ -895,7 +895,7 @@ def arel_engine
       # not use the default_scope:
       #
       #   Post.unscoped {
-      #     limit(10) # Fires "SELECT * FROM posts LIMIT 10"
+      #     Post.limit(10) # Fires "SELECT * FROM posts LIMIT 10"
       #   }
       #
       # It is recommended to use block form of unscoped because chaining unscoped with <tt>scope</tt>