Update the module type syntax

[tatchi]

To match the new type declaration implemented in #68

module type Hashable = [%import: (module Hashtbl.HashedType)] would become module type%import Hashable = Hashtbl.HashedType

[tatchi]

@ejgallego it doesn't seem I've the right to change the milestone. Do you mind doing it?

[ejgallego]

Ooops, I've tried to fix the permissions, you should have an invite.