[llvm] [RISCV] Add documentation in the LangRef on GHC CC (PR #72762)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

Thanks for the review! I'll wait a couple days to see if anyone else has comments and then I'll land it at that point.

https://github.com/llvm/llvm-project/pull/72762