[doc] python and virtualenv

win/setup/python.md

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+
+
+# download and install latest version
+
+- download from [python for windows](https://www.python.org/downloads/windows/)
+- check `Add To Path` path during installation
+
+# setup pip mirror
+
+create `$HOME\pip\pip.ini`
+```ini
+[global]
+#index-url = https://pypi.tuna.tsinghua.edu.cn/simple
+index-url = https://mirrors.aliyun.com/pypi/simple
+```
+
+
+# alternative versions and virtualenv
+
+- download alternative versions you need from [python for windows](https://www.python.org/downloads/windows/) (note: not all releases provide binary installer)
+- __DO NOT__ check `Add To Path` option during installation
+- run `pip install virutalenv`
+- run `virtualenv -p $env:LOCALAPPDATA\Programs\Python\PythonXX\python.exe env` to create virtual env for your project
+- run `env\Scripts\activate.ps1` on PowerShell to activate the virtualenv
+- run `deactivate` when done