Remove Windows version information

It has been out of date for some time.

README.txt

@@ -64,9 +64,8 @@ The Windows version of TigerVNC contains the following programs:
   winvnc - the TigerVNC Server for Windows.  winvnc allows a Windows desktop to
            be accessed remotely using a VNC viewer.
 
-The Windows version of TigerVNC should work on Windows 2000 and later.  On
-Windows XP and later, winvnc may not work if the Fast User Switching or Remote
-Desktop features are in use.
+winvnc may not work if the Fast User Switching or Remote Desktop features are
+in use.
 
 
 Unix/Linux-Specific (not Mac)