Clarify Windows support in README

[winks]

I just tried this out on Win7, with unexpected results:

Top is PowerShell, bottom is Cmder.

Not totally sure if it's the font, or wrong version of PowerShell.

[p-e-w]

Not sure what to say here. I haven't been anywhere near a Windows system in years so I have to rely on others for questions about Windows support.

In this issue, I was informed that PowerShell was working, with a screenshot to prove it. That's all the information I have.

[winks]

That original screenshot's (in #4 ) second line says Copyright (C) 2016 whereas mine (on Win7) says Copyright (C) 2009 so I can only assume the folks tested it on Win10 (same as WSL, which is only available for Win10).

Anyway, I'm not really interested in Windows support, I was just curious, so I tested it, and filed an issue.

Feel free to ignore, close, or keep it open, no hard feelings :)
Maybe it's worth clarifying that it works on Win10 or someone at some time will find out how one can make it work on Win 7/8 - but I'm no position to do that for lack of said versions.

[p-e-w]

I'm going to keep this issue open as I'm still not sure exactly which versions of PowerShell are actually supported. Unfortunately, there appears to be zero official documentation on the subject of ANSI escape sequence support in PowerShell (I'd love to be proven wrong on this!).

[Sidneys1]

Just a note, see this StackOverflow about setting the VirtualTerminalLevel/SetConsoleMode: https://stackoverflow.com/a/51681675. I did have to manipulate this to get it working in PowerShell Core, but not in Windows PowerShell. The | Out-Host trick did not work right away, but after changing the current codepage to utf8 it seemed to work as well as it did without Out-Host.