docs: where the NVIDIA descriptor-heap faults stand on 615.78.08

The heap acceleration-structure read still needs the rewrite on
615.78.08; the READMEs say so and point at HeapASRead --no-workaround
for checking a newer driver. Dynamic descriptor indexing in hit shaders
is fixed there, which the README and the Sponza and SponzaBench notes
now say, and the VulkanTriangle investigation no longer contradicts
itself about llvmpipe, which advertises VK_EXT_descriptor_heap now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/Sponza/README.md

@@ -20,6 +20,11 @@ below.
 
 ## Native RT limitation: dynamic `descriptor_heap` indexing in hit shaders
 
+Fixed in NVIDIA `615.78.08`: `tests/HeapDynamicIndexHit` selects buffers and
+textures with a runtime index in a closest-hit, including different
+descriptors in neighbouring lanes of a wave. This example still uses the
+spec-constant pattern below, which also runs on the older drivers.
+
 On NVIDIA driver `610.43.02` (Vulkan 1.4), indexing a
 `layout(descriptor_heap)` array with a **runtime (non-constant)** index
 inside a ray-tracing **hit** shader aborts the device with
@@ -122,8 +127,6 @@ This is precisely what the WebGPU path already does — bucketed texture
 arrays plus a single geometry buffer — so it is a proven, cross-backend
 pattern, and it sidesteps the NVIDIA RT fault on the native path.
 
-Remove this section once a fixed NVIDIA driver ships and dynamic
-`descriptor_heap` indexing in hit shaders stops faulting.
 
 ## Asset fetch