dt-bindings: iio: dac: adi,ad5791: Add missing bindings document

Documenting existing bindings for this device.

The Linux driver in theory 'works' without the two supplies that I have
listed as required, but without a valid scale.  As such I've
documented it as required.

Signed-off-by: Jonathan Cameron <[email protected]>
Cc: Michael Hennerich <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Acked-by: Nuno Sá <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

0 files changed, 0 insertions, 0 deletions