Second part of !50.
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v4: vkd3d-shader/hlsl: Add field-level documentation to struct hlsl_scope.
vkd3d-shader/hlsl: Add field-level documentation to function structs.
vkd3d-shader/hlsl: Add field-level documentation to struct hlsl_buffer.
vkd3d-shader/hlsl: Add documentation to small hlsl.h structs.
vkd3d-shader/hlsl: Add field-level documentation to struct hlsl_deref.
https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/61