This has been changed. Please read the article SharePoint updates are no longer available through Windows Update.
Starting with the release of SharePoint Server February 2015 Cumulative Updates Microsoft announced to push its SharePoint product updates including non-security updates through Windows Update.
I strongly advise against installing SharePoint updates using Windows Updates or WSUS! From my perspective it’s SharePoint updates should be disabled in Windows Update or WSUS or at least set to “Download the updates automatically and notify when they are ready to be installed”.
But if you decide to install the updates through Windows Update / WSUS anyway you may configure Windows Update / WSUS to push SharePoint fixes directly to your farm servers. After installing the updates make sure you run the SharePoint Configuration Wizard on every SharePoint server.