Added "Using, Understanding, and Unraveling The OCaml Language: From Practice...

Added "Using, Understanding, and Unraveling The OCaml Language:  From Practice to Theory and vice versa"

free-programming-books.md

@@ -1096,7 +1096,7 @@ See also [TeX](#tex)
 * [Real World OCaml](https://realworldocaml.org/v1/en/html/)
 * [Think OCaml](http://greenteapress.com/thinkocaml/index.html) - Allen B. Downey and Nicholas Monje
 * [Unix System Programming in OCaml](http://ocamlunix.forge.ocamlcore.org/)
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+* [Using, Understanding, and Unraveling The OCaml Language:  From Practice to Theory and vice versa](http://pauillac.inria.fr/~remy/cours/appsem/) - Didier R´emy
 
 ###Octave
 * [Octave Programming](http://en.wikibooks.org/wiki/Octave_Programming_Tutorial)