gpt: doc: Update gpt command's help description

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/common/cmd_gpt.c b/common/cmd_gpt.c
index 6bea2c7..12419b6 100644
--- a/common/cmd_gpt.c
+++ b/common/cmd_gpt.c
@@ -367,7 +367,10 @@
 U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt,
 	"GUID Partition Table",
 	"<command> <interface> <dev> <partitions_list>\n"
-	" - GUID partition table restoration\n"
-	" Restore GPT information on a device connected\n"
+	" - GUID partition table restoration and validity check\n"
+	" Restore or verify GPT information on a device connected\n"
 	" to interface\n"
+	" Example usage:\n"
+	" gpt write mmc 0 $partitions\n"
+	" gpt verify mmc 0 $partitions\n"
 );