How to exclude module but include class of that module in RDoc

Question

Running RDoc doesn't make sense for some modules that are blank. For example:

 class moduleName::className < ActiveRecord::Base

 def foo
 end

 def bar
 end

 end

RDoc produces report:

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

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

Any help would be appreciated, thank you.