Minor documentation improvements.

Bootloaders/CDC/BootloaderAPI.c

Bootloaders/CDC/BootloaderAPI.h

Bootloaders/CDC/BootloaderAPITable.S

Bootloaders/CDC/BootloaderCDC.c

Bootloaders/CDC/BootloaderCDC.h

Bootloaders/CDC/Config/AppConfig.h

Bootloaders/CDC/Config/LUFAConfig.h

Bootloaders/CDC/Descriptors.c

Bootloaders/CDC/Descriptors.h

Bootloaders/DFU/BootloaderAPI.c

Bootloaders/DFU/BootloaderAPI.h

Bootloaders/DFU/BootloaderAPITable.S

Bootloaders/DFU/BootloaderDFU.c

Bootloaders/DFU/BootloaderDFU.h

Bootloaders/DFU/Config/AppConfig.h

Bootloaders/DFU/Config/LUFAConfig.h

Bootloaders/DFU/Descriptors.c

Bootloaders/DFU/Descriptors.h

Bootloaders/HID/BootloaderHID.c

Bootloaders/HID/BootloaderHID.h