[doxygen] fix doxygen in components

dumux/material/components/CMakeLists.txt

dumux/material/components/CaO.hh

dumux/material/components/CaO2H2.hh

dumux/material/components/air.hh

dumux/material/components/benzene.hh

dumux/material/components/brine.hh

dumux/material/components/ch4.hh

dumux/material/components/co2.hh

dumux/material/components/co2tablereader.hh

dumux/material/components/component.hh

dumux/material/components/constant.hh

dumux/material/components/h2.hh

dumux/material/components/h2o.hh

dumux/material/components/heavyoil.hh

dumux/material/components/iapws/common.hh

dumux/material/components/iapws/region1.hh

dumux/material/components/iapws/region2.hh

dumux/material/components/iapws/region4.hh

dumux/material/components/lnapl.hh

dumux/material/components/mesitylene.hh