Docs: note about using Val_int(-1) on OCaml 4.02
Docs: note about using Val_int(-1) on OCaml 4.02

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c-cube/lwt,ocsigen/lwt,ocsigen/lwt,rneswold/lwt,rneswold/lwt,c-cube/lwt,ocsigen/lwt,c-cube/lwt,rneswold/lwt