ASoC: audio-graph-card2-custom-sample: Add connection image

Audio Graph Card2 is supporting many type of Sound connections, but
thus it is very difficult to understand how these are connected.

To support well understanding, adds each connection images and indicates
each settings are for where.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87pm0e4ezi.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>