[issue21745] Devguide: mention requirement to install Visual Studio SP1 on Windows

[Berker Peksag]

Changes by Berker Peksag <berker.peksag at gmail.com>:


----------
components: +Devguide -Documentation
nosy: +ezio.melotti, steve.dower, zach.ware

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21745>
_______________________________________