[llvm] [docs][tools][DirectX] Document DXContainer debug info parts (PR #204021)

[Vladislav Dzhidzhoev via llvm-commits]

dzhidzhoev wrote:

> This looks great, thanks!

Thank you!
Since https://github.com/llvm/llvm-project/pull/204166 does not implement `/Fd` and `/Qembed_debug` in clang-dxc anymore, there is some sort of difference between what original DXC offers and what will be implemented in clang-dxc when the mentioned patch gets merged.
To reflect that, I have modified the table with flags description, so that now it refers to original dxc flags, and explains what is implemented in clang-dxc:


<img width="1598" height="1514" alt="image" src="https://github.com/user-attachments/assets/7b87fcc5-b0ca-4a06-8659-852b6dffe67b" />


https://github.com/llvm/llvm-project/pull/204021