OPAM tutorial

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

OPAM is getting stable and (by extension) Mirage is also getting easier to use! 
Thomas and team have written a neat tutorial about it here:

https://github.com/OCamlPro/opam/wiki/Creation-of-OPAM%C2%A0packages

I'm flowing my way through all the mirage-www to make it consistent again 
(before I give a talk in Princeton next week about it).

-anil