Add a note to the README

Explain that the verification scrpt will report a warning
for a correctly generated git-log

Components: Vulkan

Change-Id: Ie8e0ab090f50c776150f9a7f4ce7d69583186953
diff --git a/external/vulkancts/ b/external/vulkancts/
index f2f7559..4a003ab 100644
--- a/external/vulkancts/
+++ b/external/vulkancts/
@@ -307,6 +307,9 @@
 	python external/vulkancts/scripts/ VK_11_Khronos_1/ external/vulkancts/mustpass/1.1.0/vk-default.txt
+Please note that the script reports a warning even for a correctly generated git-log.txt
+If your git-log.txt contains only head commit of the release tag then
+the warning can be ignored.
 Vulkan platform port