[llvm] [Docs][RISCV] Document RISC-V vector codegen (PR #96740)

[Fraser Cormack via llvm-commits]

https://github.com/frasercrmck commented:

In general this looks great, thank you!

I'm not arguing particularly strongly in favour of this suggestion -- and despite me being a native speaker I'm still not 100% on this -- but when the phrase "fixed length" is used as an adjective, as in "fixed-length vector", then it's technically best to use the hyphenated form. As in, "a fixed-length vector has a fixed length". Same with certain uses of "target-agnostic" vs "target agnostic". Again, I don't want to be too prescriptive on this matter and it's not a blocker for me.

https://github.com/llvm/llvm-project/pull/96740