winrt: Update `VulkanRT-License.txt` text
winrt: Update `VulkanRT-License.txt` text

Change-Id: I7bcd0962fa970323f34ea501148c0f5b120541a0

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools