Microsoft released build 10162 of Windows 10 to members of its Windows Insider program on Thursday. However, the release notes for a newer, and currently unreleased, version of the OS, build 10163, have since been posted on the Internet.
As with many of these leaks, they come from "WZor", who has been posting release notes and screenshots for unreleased Windows 10 builds for the past several months. As you might imagine, the release notes are all about fixing bugs in this build, along with some known issues. This is not a surprise as Microsoft has already indicated that future preview builds of Windows 10 will mainly be about fixing issues before the OS is officially released on July 29.
In the meantime, Microsoft released three new official preview builds of Windows 10 in the space of just four days this week, and it's likely that the company will continue that kind of rapid release schedule to fix the remaining bugs in the last four weeks or so before the launch date arrives.