Missing 1.8 release change log?

So, where can I find this log? Or it not even exists?
But it has been more than half year after 1.8 release, I am seeking valuable source code to merge into my old Urho3D 1.7.1 based project.

https://github.com/urho3d/Urho3D/compare/1.7.1...1.8

TL;DR: It doesn’t exist, everyone was too lazy to do it.

If you just compare Source/Urho3D between 1.7.1 and 1.8, it should give you enough info.
There are a couple of bug fixes, render-UI-to-texture support, kNet replaced with SLikeNet… nothing else of note.