-- initial import of the OCaml teaching resources page

This is the first import of the wiki page for OCaml teaching resources [1]

[1]  https://github.com/ocaml/ocaml.org/wiki/OCAML-Teaching-Resources
Looking through the other book list, I do think it's useful to have additional books on this teaching page that could help educators. For example, the book on Purely Functional Datastructures might be useful but it doesn't belong on the OCaml books page.

The only book we need to add to our books page is the new More OCaml, tracked in #554.