rename CFG_ENV_IS_IN_DATAFLASH in CONFIG_ENV_IS_IN_DATAFLASH

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/README b/README
index 4823255..baa06e0 100644
--- a/README
+++ b/README
@@ -2242,7 +2242,7 @@
 	  The size in bytes of the EEPROM device.
 
 
-- CFG_ENV_IS_IN_DATAFLASH:
+- CONFIG_ENV_IS_IN_DATAFLASH:
 
 	Define this if you have a DataFlash memory device which you
 	want to use for the environment.