How to exclude a module, but include the class of this module in RDoc

Question

Running RDoc does not make sense for some modules that are empty. For instance:

 class moduleName::className < ActiveRecord::Base

 def foo
 end

 def bar
 end

 end

RDoc produces a report:

moduleName -> blank HTML
moduleName::className -> complete documentation

How to get remove moduleName, which is empty from report generation?

Any help would be appreciated, thanks.