Update build documentation

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

www/building.xml

@@ -70,8 +70,8 @@ well without it, so you'll still have to install it later.</p>
     <li><tt>make install</tt> <i>(If you want to install it)</i></li>
   </ul>
 
-<p>Note that OpenConnect will attempt to use the OpenSSL library by default.
-If you want it to use GnuTLS instead, then add <tt>--with-gnutls</tt> to the
+<p>Note that OpenConnect will attempt to use the GnuTLS library by default.
+If you want it to use OpenSSL instead, then add <tt>--without-gnutls</tt> to the
 <tt>./configure</tt> command above.</p>
 
 <p>If compilation fails, please make sure you have a working compiler and the
@@ -84,6 +84,8 @@ it still doesn't build, please send the full output in a plain-text mail to the
 <p>Mac OS X users will also need to install the
 <a href="http://tuntaposx.sourceforge.net/">Mac OS X tun/tap driver</a>, and Solaris/OpenIndiana users will need the <a href="http://www.whiteboard.ne.jp/~admin2/tuntap/">Solaris one</a>. Note that for IPv6 support, the Solaris tun/tap driver from 16th Nov 2009 or newer is required.</p>
 
+<p>On Windows, version 9.9 or later of the <a href="https://community.openvpn.net/openvpn/wiki/ManagingWindowsTAPDrivers">TAP-Windows driver</a> from the <a href="http://www.openvpn.net/">OpenVPN project</a> is required. The easiest way to install the driver is to use the Windows installer from the <a href="http://openvpn.net/index.php/download/community-downloads.html">Community Downloads page</a>. The 64-bit installer contains signed drivers suitable for use on Windows 7 and later versions.</p>
+
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