If you're looking for the release notes for V5.1, they're on the same place on our website where they've always been:
https://www.simplify3d.com/products/sim ... ase-notes/
The features for V5.1 were actually selected based on the most popular requests we received from customers. If you look at many of the threads on our forum, you can see that things like ironing, OctoPrint support, monotonic infill, etc were all extremely popular requests.
We are certainly monitoring this request as well to see if it's something that could be considered for a future release.