[clang] [llvm] [RISCV] Add Svrsw60t59b extension (PR #132321)

[Sam Elliott via llvm-commits]

lenary wrote:

> > Please can you add information about this to llvm/docs/RISCVUsage.rst ?
> 
> Looks like RISCVUsage.rst is there. Are you looking for something more?

No. Sorry I missed that.

https://github.com/llvm/llvm-project/pull/132321