[clang] [llvm] [DirectX] Start documenting DXIL Resource handling (PR #90553)

[Damyan Pepper via cfe-commits]

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@@ -29,6 +29,7 @@ pointer of the template parameter type. The pointer is populated from a call to
 data through until lowering in the backend.
 
 Resource types are annotated with the ``HLSLResource`` attribute, which drives
-code generation for resource binding metadata. The ``hlsl`` metadata nodes are
-transformed in the backend to the binding information expected by the target
-runtime.
+code generation into target extension types in IR. These types are target
+specific and differ between DXIL and SPIR-V generation, providing the necessary
+information for the targets to generate binding metadata for their respective
+target runtimes.
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damyanp wrote:

I think that this needs to be reconciled with #98419?

https://github.com/llvm/llvm-project/pull/90553