wiki windows installation page

[Nicholas Jankowski]

After a user fumbled through installing two outdated versions of
Octave because they insisted on following scattered instructions, I
updated the info on the Wiki [1] for v4,2.0 (it still had 4.0.3 as the
most recent version).  Two questions:

1 - Is it necessary to move cygwin instructions under the 4.2.0
section? If so, can they just be moved from the 4.0.3 section or does
antyhing need to be changed?

2 - Windows zip version includes both octave.bat and octave.vbs.  I
think the .vbs was added as a part of bug # 41074 [2].  Is there a
particular reason to tell the user to make a shortcut to one or the
other?

[1] http://wiki.octave.org/Octave_for_Microsoft_Windows
[2] https://savannah.gnu.org/bugs/?41074

Nick J.