Doc fix (closes #4609)

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4174 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/associations.rb

@@ -635,7 +635,7 @@ def has_one(association_id, options = {})
       #   is used on the associate class (such as a Post class). You can also specify a custom counter cache column by given that
       #   name instead of a true/false value to this option (e.g., <tt>:counter_cache => :my_custom_counter</tt>.)
       # * <tt>:include</tt>  - specify second-order associations that should be eager loaded when this object is loaded.
-      # # <tt>:polymorphic</tt> - specify this association is a polymorphic association by passing true.
+      # * <tt>:polymorphic</tt> - specify this association is a polymorphic association by passing true.
       #
       # Option examples:
       #   belongs_to :firm, :foreign_key => "client_of"