KhronosGroup
Add entry for VK_KHR_fragment_shading_rate
We recently noticed that there's no guide entry for this extension - however there is a Khronos blog post here: https://www.khronos.org/blog/khronos-vulkan-working-group-releases-shading-rate-extension-to-increase-rendering-performance-and-quality
Would be good if an entry could be added; much of the text in the blog post can probably be used directly?
As an additional point, it would probably be useful to draw parallels to the D3D12 "Variable Shading Rate" functionality - noting how these are intended to behave the same.
Related - it would be good to explain the differences between this extension and VK_EXT_fragment_density_map. At first glance, they look pretty similar, but the details are quite different.
