boards/nucleo*: fix doxygen parent group

boards/nucleo-f030/include/periph_conf.h

boards/nucleo-f070/include/periph_conf.h

boards/nucleo-f072/include/periph_conf.h

boards/nucleo-f091/include/periph_conf.h

boards/nucleo-f103/include/periph_conf.h

boards/nucleo-f302/include/periph_conf.h

boards/nucleo-f303/include/periph_conf.h

boards/nucleo-f334/include/periph_conf.h

boards/nucleo-f401/include/periph_conf.h

boards/nucleo-f410/include/periph_conf.h

boards/nucleo-f411/include/periph_conf.h

boards/nucleo-f446/include/periph_conf.h

boards/nucleo-l053/include/periph_conf.h

boards/nucleo-l073/include/periph_conf.h

boards/nucleo-l152/include/periph_conf.h

boards/nucleo-l476/include/periph_conf.h

boards/nucleo144-f207/include/periph_conf.h

boards/nucleo144-f303/include/periph_conf.h

boards/nucleo144-f412/include/periph_conf.h

boards/nucleo144-f413/include/periph_conf.h