nyan-big: add padding to its file

Without this padding nyan-big ends at a blank screen on boot.
Details on how to get to this padding can be found in the README.chromium under Notes.

Signed-off-by: Tristan Bastian <tristan-c.bastian@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/doc/chromium/nyan-big.its b/doc/chromium/nyan-big.its
index 37d4e10..bd41291 100644
--- a/doc/chromium/nyan-big.its
+++ b/doc/chromium/nyan-big.its
@@ -6,7 +6,7 @@
 
 	images {
 		kernel {
-			description = "U-Boot mainline";
+			description = "U-Boot mainline    ";
 			type = "kernel_noload";
 			arch = "arm";
 			os = "linux";