[llvm] [DirectX] [NFC] Revise descriptions of DXIL module flags (PR #133543)

[Finn Plummer via llvm-commits]

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@@ -17,7 +17,7 @@ CONTAINER_PART(PSG1)
 // SHADER_FEATURE_FLAG(bit offset for the shader info flag, bit offset for DXIL module flag, name, description.
 
 SHADER_FEATURE_FLAG(0,   2, Doubles, "Double-precision floating point")
-SHADER_FEATURE_FLAG(1,  17, ComputeShadersPlusRawAndStructuredBuffers, "Raw and Structured buffers")
+SHADER_FEATURE_FLAG(1,  17, ComputeShadersPlusRawAndStructuredBuffers, "CS4 raw and structured buffers")
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inbelic wrote:

What does `CS4` mean/denote? We are also not currently checking for it in the `FileCheck`

https://github.com/llvm/llvm-project/pull/133543