Is bootcamp 6.0 supporting Target Display mode of an Imac to a Windows 10 OS?
Nope, this is not possible. Target display mode only works if both machine are in macOS, as mentioned in the Apple KB article Use your iMac as a display with Target Display Mode.


  If your iMac is currently started up in Windows, it won't enter Target Display Mode. Target Display Mode isn't supported in Boot Camp.