layers: Update layer details doc
layers: Update layer details doc

For new sampleCount/Image tests

Change-Id: Ie857e56b38170e343486f2958a4d5afe7fcdcc12

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