rename CFG_ENV_IS_IN_NVRAM in CONFIG_ENV_IS_IN_NVRAM

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/README b/README
index 6481186..0da6412 100644
--- a/README
+++ b/README
@@ -2174,7 +2174,7 @@
 accordingly!
 
 
-- CFG_ENV_IS_IN_NVRAM:
+- CONFIG_ENV_IS_IN_NVRAM:
 
 	Define this if you have some non-volatile memory device
 	(NVRAM, battery buffered SRAM) which you want to use for the