lightbar: document how it all works
lightbar: document how it all works

Add a huge comment so people can figure this out easier.

BUG=none
BRANCH=none
TEST=make buildall

Change-Id: I042a209c06023210b8ad53d138971ffee4b89ab7
Signed-off-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/294179
Reviewed-by: Todd Broch <035f5b1f817cbb94019cec357b99778115602b63@chromium.org>

coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics