vk.xml path inconsistency in CMakeLists.txt

[timo-suoranta-varjo]

In Vulkan-Hpp/CMakeLists.txt, path to vk.xml in has some inconsistency.
VulkanRegistry_DIR cannot point to Vulkan-Docs, because inside it vk.xml is inside xml directory.
Meanwhile, Vulkan-Hpp CMakeLists.txt expects vk.xml to be found from directory called registry.

One possible solution is to move Vulkan-Headers/registry/vk.xml to Vulkan-Headers/registry/xml/vk.xml.

IMHO it is not ideal that Vulkan-Headers keeps copy of registry from Vulkan-Docs. It would be better to simply use files from Vulkan-Docs directly.

[asuessenbach]

VulkanRegistry_DIR is supposed to point to Vulkan-Headers/registry, not to Vulkan-Docs
That said, we're currently using it wrong, expecting it would point to Vulkan-Headers, I will adjust it accordingly!

[timo-suoranta-varjo]

Presumably then VulkanRegistry_DIR can also point to Vulkan-Docs/xml?
Why Vulkan-Headers is used in the middle at all, why not use Vulkan-Docs directly?