cmd: correct short text for tftpboot

The command's name is a misnomer.
The command loads a file but does not run (boot) it.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/net.c b/cmd/net.c
index 527ac84..46f8c87 100644
--- a/cmd/net.c
+++ b/cmd/net.c
@@ -46,7 +46,7 @@
 
 U_BOOT_CMD(
 	tftpboot,	3,	1,	do_tftpb,
-	"boot image via network using TFTP protocol",
+	"load file via network using TFTP protocol",
 	"[loadAddress] [[hostIPaddr:]bootfilename]"
 );
 #endif