chore: update CLI installation instructions for Windows (coder#816)

cli/installation.md

@@ -23,15 +23,25 @@ version number.
 brew install cdr/coder/coder-cli
 ```
 
-### Download (Windows, Linux, Mac)
+### Download (Linux, Mac)
 
 Download releases [from GitHub](https://github.com/coder/coder-cli/releases):
 
 1. Click a release and download the tar file for your operating system (ex:
-   coder-cli-linux-amd64.tar.gz)
+   `coder-cli-linux-amd64.tar.gz`)
 1. Extract the `coder` binary and copy it to a location you've added to your
    `PATH` environment variable
 
+### Download (Windows)
+
+1. Click a release (e.g., `coder-cli-windows.zip`) and download the file
+1. Unzip the file
+1. Copy the file to a location of your choosing (e.g., `%USERPROFILE%\bin`).
+1. On the command-line interface, execute `coder.exe login`
+
+> Make sure that your user's `PATH` environment variable contains the location
+> you chose in step 3.
+
 ## Authenticate
 
 Once you've installed the CLI, authenticate the client with your Coder account.