Update install script and readme for windows

Author: laureanray

README.md

@@ -12,7 +12,15 @@ Shell Installation (Mac, Linux)
 curl -fsSL https://raw.githubusercontent.com/laureanray/clibgen/main/install.sh | sh
 ```
 
-PowerShell Installation (Work in progress)
+PowerShell Installation (Windows)
+```powershell
+iwr https://raw.githubusercontent.com/laureanray/clibgen/main/install.sh -useb | iex
+```
+
+Manual Installation (Binaries)
+- Download the file for your platform and version you need in the [releases page](https://github.com/laureanray/clibgen/releases) 
+- Extract to where you store your binaries
+- Add the binaries directory to your PATH
 
 ### Usage 
 

install.ps1

@@ -0,0 +1,54 @@
+#!/usr/bin/env pwsh
+# Copyright 2022 Laurean Ray Bahala. All rights reserved. MIT license.
+# TODO(everyone): Keep this script simple and easily auditable.
+
+$ErrorActionPreference = 'Stop'
+
+if ($v) {
+  $Version = "v${v}"
+}
+if ($args.Length -eq 1) {
+  $Version = $args.Get(0)
+}
+
+$ClibgenInstall = $env:CLIBGEN_INSTALL
+$BinDir = if ($ClibgenInstall) {
+  "$ClibgenInstall\bin"
+} else {
+  "$Home\.clibgen\bin"
+}
+
+$ClibgenZip = "$BinDir\clibgen.zip"
+$ClibgenExe = "$BinDir\clibgen.exe"
+$Target = 'Windows-x86_64'
+
+# GitHub requires TLS 1.2
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+
+$ClibgenUri = if (!$Version) {
+  "https://github.com/laureanray/clibgen/releases/latest/download/clibgen_${Target}.zip"
+} else {
+  "https://github.com/laureanray/clibgen/releases/download/${Version}/clibgen_${Target}.zip"
+}
+
+Write-Output $ClibgenUri
+
+if (!(Test-Path $BinDir)) {
+  New-Item $BinDir -ItemType Directory | Out-Null
+}
+
+curl.exe -Lo $ClibgenZip $ClibgenUri
+
+tar.exe xf $ClibgenZip -C $BinDir
+
+Remove-Item $ClibgenZip
+
+$User = [EnvironmentVariableTarget]::User
+$Path = [Environment]::GetEnvironmentVariable('Path', $User)
+if (!(";$Path;".ToLower() -like "*;$BinDir;*".ToLower())) {
+  [Environment]::SetEnvironmentVariable('Path', "$Path;$BinDir", $User)
+  $Env:Path += ";$BinDir"
+}
+
+Write-Output "Clibgen was installed successfully to $ClibgenExe"
+Write-Output "Run 'clibgen --help' to get started"