llvm-project

6925caee - [Docs][DirectX] Add relevant documentation of Root Signature (#149608)

[Docs][DirectX] Add relevant documentation of Root Signature (#149608) This pr adds documentation of root signatures for reference of an LLVM user. The target audience is an LLVM user that wants to build a custom tool, or front-end, that requires constructing a root signature part (RTS0) for a `DXContainer`. With that in mind, this pr adds documentation of the metadata representation of root signatures implemented in LLVM and utilized in Clang.