Earlier the PBIAS regulator was optional, not so with recent
omap_hsmmc changes. To make things easier for people with
custom .config files, let's add minimal documentation for it
as suggested by Russell King .
This file contains documentation for running mainline
kernel on omaps.
KERNEL NEW DEPENDENCIES
v4.3+ Update is needed for custom .config files to make sure
CONFIG_REGULATOR_PBIAS is enabled for MMC1 to work
properly.
