Changes to ENet documentation

Hello!

I've made some changes to the ENet prox operator documentation, and I'd like to submit a pull request and have it looked at.

I've put it in my own branch on my machine - but when I try to make a PR I get told that I'm not authenticated to do that.

More generally, I've got time until the new year to write some more documentation or I could re implement some of my PhD work on fully distributed ADMM (but I'd need help!).

Tom