Add choco instructions for windows

windows/Readme.md

+# Prerequisites
+https://chocolatey.org/install
+* Powershell
+```
+Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))
+```
+* Configure proxy
+```
+choco config set proxy http://127.0.0.1:3128
+# for vm setup (use vbox host only network)
+choco config set proxy http://192.168.200.1:3128
+```
+
+choco install -y firefox vagrant virtualbox
+
+googlechrome atom 7zip
+choco install git --params="'/GitAndUnixToolsOnPath /NoAutoCrlf'" -y