This:
- Updates syncWord comments after changing it from uint16_t to uint8_t
in commit 55aff74a ([SX126x] Changed pin mapping, added reset,
changed LoRa sync word to 1B).
- Adds missing useRegulatorLDO comments forgoten in commit ea85a663
([SX126x] Pass useRegulatorLDO to SX1262/SX1261/SX1268).
- Makes useRegulatorLDO comments the same in all places (using the more
explicit version).
- Fixes a typo in the doxygen \parma -> \param command.
