Microsoft looks to be pushing out an update to Windows 10 for users that are on the Insider preview via Windows Update this afternoon. The update is labeled "Windows 10 Insider Preview October Update for x64-based Systems", and carries the support number KB3103470. That being said, it's not entirely clear yet what this update addresses.
There is a link to the support information for this update on Microsoft's support database, but it isn't populated with anything just yet. Still, if you want to keep an eye out, you can monitor the page here, and we'll update this post with the changes if and when Microsoft posts them.
Update: Microsoft has now published information on the update via its support website, simply stating: "This update includes improvements to enhance the functionality of Windows 10" and it seems heavily related to updates to Notepad.