Microsoft has dropped a new update for Windows 10 devices. KB3140741 is a small ‘servicing stack update’ and doesn’t require reboot after install.
Microsoft has not revealed much about the update but the support page for KB3140741 says “This update makes stability improvements for Windows 10 Version 1511 servicing stack.”
The update size is 5MB for x86 installation and 11MB for x64 installation of Windows 10. A reboot is not required for installation of this update. It is worth noting that update KB3140741 isn’t a cumulative update and it doesn’t change Windows 10 build.
The servicing stack update should be downloaded and installed automatically. You can also force update via Settings > Update and security > Check for updates.