Add clarification than ldbox is a fork of sb2 to README.
Add clarification than ldbox is a fork of sb2 to README.

Signed-off-by: Oleg Girko <665b39a1e96a9a15fc99f73183af3f04bf8111eb@infoserver.lv>

OlegGirko/ldbox,ldbox/ldbox,OlegGirko/ldbox,ldbox/ldbox,ldbox/ldbox,OlegGirko/ldbox,OlegGirko/ldbox,OlegGirko/ldbox,ldbox/ldbox,ldbox/ldbox,ldbox/ldbox,OlegGirko/ldbox