[docs] Troubleshooting Failed Python Installation on Windows

[Laura Creighton]

webmaster gets a lot of mail from people who cannot install their
Pythons.  I can handle the obvious problems -- 'that download is for a
Mac -- your download is fine, your PATH is not -- Try looking for
Python3, because you are finding your old Python 2 install, not this
new onë́' but most of the time, I have no clue.  I send the people to
python-list or the bug tracker, but mostly they never show up there.

How hard would it be for windows-using developers to write such a
thing?  It would make a lot of people's life a lot easier.

Laura