Alternate install instructions

[ghost]

I read the instruction here:

https://fdopen.github.io/opam-repository-mingw/installation

however I discovered you can install OCaml without Opam, for example:

s1=https://dl.bintray.com/fdopen/prebuild-win32-ocaml-packages
s2=4.09.0
curl -L -O "$s1"/"$s2"+mingw64c.tar.xz
tar -x -f "$s2"+mingw64c.tar.xz
cd ocaml-variants."$s2"+mingw64c
echo 'print_endline "sunday"' > sunday.ml
PATH=bin:$PATH
export OCAMLLIB=lib/ocaml
ocamlopt -o sunday sunday.ml

I think this should be documented somewhere.