Fix Docu: use 64-bit version of OCaml compiler
Fix Docu: use 64-bit version of OCaml compiler

From what I gather, the 32-bit version of the OCaml compiler current won't compile F*, so in this manual, it really must be the 64-bit version. I'm working through the steps in the instructions right now, and it doesn't work with the 32-bit version.
FStarLang/FStar,A-Manning/FStar,A-Manning/FStar,A-Manning/FStar,FStarLang/FStar,FStarLang/FStar