Add prerelease options to installation docs

Also fix an issue where the npm instructions got put in the middle of
the curl instructions.

Author: devm33

README.md

@@ -45,28 +45,40 @@ Install with [WinGet](https://github.com/microsoft/winget-cli) (Windows):
 winget install GitHub.Copilot
 ```
 
+```bash
+winget install GitHub.Copilot.Prerelease
+```
+
 Install with [Homebrew](https://formulae.brew.sh/cask/copilot-cli) (macOS and Linux):
 
 ```bash
 brew install copilot-cli
 ```
 
-Install with the install script (macOS and Linux):
+```bash
+brew install copilot-cli@prerelease
+```
+
+Install with [npm](https://www.npmjs.com/package/@github/copilot) (macOS, Linux, and Windows):
 
 ```bash
-curl -fsSL https://gh.io/copilot-install | bash
+npm install -g @github/copilot
 ```
 
-Or
+```bash
+npm install -g @github/copilot@prerelease
+```
+
+Install with the install script (macOS and Linux):
 
 ```bash
-wget -qO- https://gh.io/copilot-install | bash
+curl -fsSL https://gh.io/copilot-install | bash
 ```
 
-Install with [npm](https://www.npmjs.com/package/@github/copilot) (macOS, Linux, and Windows):
+Or
 
 ```bash
-npm install -g @github/copilot
+wget -qO- https://gh.io/copilot-install | bash
 ```
 
 Use `| sudo bash` to run as root and install to `/usr/local/bin`.