doc: Update Sphinx documentation #296

Job	Run time
lint	42s
check-versions	1m 55s
build (ad2s1210_iio)	1m 12s
build (ad405x_iio)	1m 13s
build (ad4130_iio)	1m 22s
build (ad559xr_console)	1m 25s
build (ad5754r_iio)	1m 23s
build (ad5770r_console)	1m 20s
build (ad579x_iio)	1m 15s
build (ad590_console)	1m 16s
build (ad5933_console)	1m 26s
build (ad7124_console)	1m 19s
build (ad7124_temperature-measure)	1m 19s
build (ad7134_iio)	1m 26s
build (ad717x_console)	1m 26s
build (ad717x_iio)	1m 26s
build (ad719x_iio)	1m 16s
build (ad7689_iio)	1m 26s
build (ad77681_iio)	1m 13s
build (ad777x_iio)	1m 16s
build (adt7420_console)	1m 22s
build (evb_discovery_firmware)	1m 16s
build (ltc2672_iio)	1m 21s
build (ltc268x_console)	1m 15s
build (nanodac_console)	1m 25s
	33m 15s

Provide feedback