Where are the ECS release notes?

Where can we see the ECS change log/release notes? I saw that preview-20 just (?) got released and would like to see what changed for example

Okey I found this: https://github.com/Unity-Technologies/EntityComponentSystemSamples/blob/master/ReleaseNotes.md but it doesnt seem to be up to date.

There is no known change log for ECS at the moment, since it’s in a super-preview state. What you have linked is the change log for the samples only.
We probably will get change logs when it will be a little bit closer to release.

I diff the versions every time and there was very little change in 20.

Pretty much only changed how chunk version is checked and a few tests.