closes #1379 by documenting can.when
closes #1379 by documenting can.when

rjgotten/canjs,rjgotten/canjs,beno/canjs,ackl/canjs,Psykoral/canjs,beno/canjs,Psykoral/canjs,rasjani/canjs,rasjani/canjs,patrick-steele-idem/canjs,patrick-steele-idem/canjs,tracer99/canjs,tracer99/canjs,ackl/canjs,gsmeets/canjs,tracer99/canjs,Psykoral/canjs,gsmeets/canjs,rasjani/canjs,rasjani/canjs,rjgotten/canjs,bitovi/canjs,gsmeets/canjs,ackl/canjs,whitecolor/canjs,Psykoral/canjs,bitovi/canjs,beno/canjs,bitovi/canjs,whitecolor/canjs,whitecolor/canjs,bitovi/canjs,patrick-steele-idem/canjs,rjgotten/canjs