drivers*: add saul doc group to related drivers

drivers/include/adcxx1c.h

drivers/include/ads101x.h

drivers/include/adxl345.h

drivers/include/bmp180.h

drivers/include/bmx055.h

drivers/include/bmx280.h

drivers/include/dht.h

drivers/include/fxos8700.h

drivers/include/grove_ledbar.h

drivers/include/hdc1000.h

drivers/include/hts221.h

drivers/include/io1_xplained.h

drivers/include/isl29020.h

drivers/include/jc42.h

drivers/include/l3g4200d.h

drivers/include/lis2dh12.h

drivers/include/lis3dh.h

drivers/include/lis3mdl.h

drivers/include/lps331ap.h

drivers/include/lsm303dlhc.h