rename CFG_ENV_IS_IN_NAND in CONFIG_ENV_IS_IN_NAND

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/README b/README
index baa06e0..6481186 100644
--- a/README
+++ b/README
@@ -2255,7 +2255,7 @@
 	  environment area within the total memory of your DataFlash placed
 	  at the specified address.
 
-- CFG_ENV_IS_IN_NAND:
+- CONFIG_ENV_IS_IN_NAND:
 
 	Define this if you have a NAND device which you want to use
 	for the environment.