sandbox: README: setting environment variables

The command to set environment variables is setenv.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/sandbox/README.sandbox b/board/sandbox/README.sandbox
index a28fc9f..ee44218 100644
--- a/board/sandbox/README.sandbox
+++ b/board/sandbox/README.sandbox
@@ -247,25 +247,25 @@
 DHCP
 ....
 
-set autoload no
-set ethact eth1
+setenv autoload no
+setenv ethact eth1
 dhcp
 
 PING
 ....
 
-set autoload no
-set ethact eth1
+setenv autoload no
+setenv ethact eth1
 dhcp
 ping $gatewayip
 
 TFTP
 ....
 
-set autoload no
-set ethact eth1
+setenv autoload no
+setenv ethact eth1
 dhcp
-set serverip WWW.XXX.YYY.ZZZ
+setenv serverip WWW.XXX.YYY.ZZZ
 tftpboot u-boot.bin
 
 The bridge also supports (to a lesser extent) the localhost interface, 'lo'.
@@ -287,7 +287,7 @@
 TFTP
 ....
 
-set ethact eth5
+setenv ethact eth5
 tftpboot u-boot.bin