We're downloading the user-guide as part of the setup, so we might as well copy it...

We're downloading the user-guide as part of the setup, so we might as well copy it to the install directory.  If someone has built a more up-to-date version of the user-guide in the docbook directory, then it will just overwrite this one, but for most developers, I don't think they're building their own, so at least this way they'll still have a local copy of the user-guide.  If optional is the preferred default, then we can change config.nmake and just comment out UG_DIR and mark as "optional" instead of "recommended".

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@45116 f5534014-38df-0310-8fa8-9805f1628bb7