Just release - vkmark: more than a Vulkan benchmark

With help from Khronos member Collabora, employee Alexandros Frantzis created vkmark, which aims to provide an extensible suite of targeted, configurable benchmarking scenes for Vulkan. Most scenes exercise specific Vulkan features or usage patterns (e.g., desktop 2.5D scenarios), although we are also happy to have more complex, visually intriguing scenes. vkmark Vulkan benchmark is available on GitHub.