grouping classes in documentation

eo/src/eoSelect.h

@@ -35,6 +35,9 @@ eoSelect selects a number of individuals from the first argument and
 puts it in the second. To emphasize that it should not try to enlarge
 the population, the second argument is an eoPopRange, a simple struct
 that holds a begin and end iterator to the population
+
+@ingroup Core
+@ingroup Selectors
 */
 template<class EOT>
 class eoSelect : public eoBF<const eoPop<EOT>&, eoPop<EOT>&, void>