This patch removes sdhc_api references since such API
does not actually exist. SD card controller drivers
use disc driver interface. Accordingly, the SDHC documentation,
which actually describes how to connect a SD card via SPI
and has little to do with SD host controller (SDHC),
is also moved to disk access page and adapted.
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
5c7787c912