Microsoft now released the full changelog of the latest firmware updates for the Surface Pro 4 last week as July 20 release.
Microsoft Releases Full Changelog for the Latest Update for Surface Pro 4
July Firmware Update brings new Surface Pro Type Cover support to Surface Pro 4
Microsoft brings new Surface Pro Type Cover and Surface Pro Signature Type Cover support to Surface Pro 4 via a firmware update. You can now get this new firmware updates on Windows Update.