Update CHANGELOG.txt

...just a minor thing: it is accustomed to have latest versions added to the top of the file (that's how the 6.x version of the CHANGELOG.txt was). So I guess you'll have to reorder the versions mentioned in the log in descending order.

Yes. I guess then it's a matter of personal taste of the maintainer. But I had core's CHANGELOG.txt in mind that lists changes with newest at the top.

Also, the way I see it, having the latest changes at the top of the file has benefits for both the people reading the file as well as for people keeping it up to date. Those reading it don't have to scroll all the way down to see what has changed compared to the previous version and those that need to update the file need only open it and start typing - no scrolling for them either. These benefits get more value as the file grows larger and larger.

Anyways, I'm sure that if you want it with oldest at the top, you have your reasons so I won't insist any further. That main goal of this issue was about updating the file to include the 7.x branch's changes. That was done, so thank you :)