out-of-date sail ocaml version in read-the-docs

[Dan Smathers]

Hi,
https://riscof.readthedocs.io/en/stable/installation.html#install-plugin-models says
opam switch create ocaml-base-compiler.4.06.1

https://github.com/rems-project/sail/blob/sail2/INSTALL.md says:

Use ocaml -version to check your OCaml version. If you have OCaml 4.08.1 or newer, that's fine, otherwise you can use opam switch to install a newer version:

opam switch create 5.1.0

Can you update the readthedocs directions to use the newer OCaml version? Otherwise my generation of the SAIL model has errors.
thanks

[shareefj]

I've just run into the same issue. When compiling sail-riscv I get:

Syntax error:
[model/riscv_sys_regs.sail]:182:25-25
182 |    else [m with F = v[F], D = v[D] & v[F]]