[llvm] [dyndbg] Add Dynamic Debugging docs (PR #210001)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

Github isn't rendering the image in `Files changed` but you can see it by clicking the `...` menu on the file and `view file`: https://github.com/llvm/llvm-project/blob/c94e1ac90951219a04c45fba18f974bc2e912535/llvm/docs/DynDbgObjLayout.png

https://github.com/llvm/llvm-project/pull/210001