pre-vcbuild win32 install docs incorrect

This patch fixes a really bad recommendation that's not been removed
from the client-only installation instructions. We removed this
recommendation as of 8.1, but it's still included in the documentation :-(

Please consider back-patching this into the 8.1 and 8.2 version of the
documentation, as it's something we really don't want people to do.

I came across this while looking at how to update that documentation to
deal with the new VC++ build stuff. I can't quite decide on how to do
that yet - do people have any strong opinions on if the new vcbuild
stuff should go in the documentation proper, or stay in
src/tools/msvc/README?

//Magnus