grouping classes in documentation

eo/src/eoConstrictedVariableWeightVelocity.h

@@ -39,6 +39,8 @@
 *   At step t: v(t+1)= K * ( w*v(t) + c1*r1* (xbest(t)-x(t)) + c2*r2* (gbest(t) - x(t)))
 *   w is updated each time the velocity performer is called and K is fixed
 *   (ci given and Ri chosen at random in [0;1]).
+*
+*   @ingroup Variators
 */
 template < class POT > class eoConstrictedVariableWeightVelocity:public eoVelocity < POT >
 {