I certainly use OpenGL (mostly GLES2 subset)... but I'm not sure I would have much to read or contribute. The OCaml-specific issues are essentially bindings. And I've fallen down the path of using glcaml which I locally change and add to. It's pretty much like using OpenGL from C except the constants are lowercase.
However, it would be nice if there was an easy answer for a new user. I had to flounder around with the existing bindings for a while. At the time, shaders weren't well supported, which is why I chose glcaml. Also because glcaml is a very minimal layer -- easy to change and add to. But I'd agree it's probably the least tested (used) and least "OCaml".
I think there's merit for a means to discuss OpenGL bindings, maybe ratifying them... starting from scratch, whatever. But when it comes to users, there is plenty of OpenGL documentation and shouldn't really be anything OCaml specific. Unless the bindings add/change a lot (in the direction of LablGL).