Update installation instructions

The maintainers do not actively publish an npm package at this time.
Update the recommended usage instructions to accurately describe the
supported technique for running the code.

README.md

@@ -28,19 +28,19 @@ which is required by the automation voice.
 
 ## Installation
 
-1. Install the project by executing the following command:
+1. Download the source code by executing the following command:
 
-       npm install -g @bocoup/windows-sapi-tts-engine-for-automation
+       git clone https://github.com/w3c/aria-at-automation-driver.git
 
 2. Run the install command in a terminal:
 
-       at-driver install
+       ./bin/at-driver install
 
    If prompted for system administration permission, grant permission.
 
 3. Start the server by executing the following command in a terminal:
 
-       at-driver serve
+       ./bin/at-driver serve
 
    The process will write a message to the standard error stream when the
    WebSocket server is listening for connections. The `--help` flag will cause