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

[Deric C. via llvm-commits]

Icohedron wrote:

I pushed a new commit that alters the descriptions of the shader flags to match the PR for an update to the DXIL documentation in the DXC repository: https://github.com/microsoft/DirectXShaderCompiler/pull/7295

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