usb: raw-gadget: update documentation

A recent patch added reporting of more event types to Raw Gadget.

Update the documentation to reflect that this feature has been
implemented.

Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20231030223158.36636-1-andrey.konovalov@linux.dev


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>