add install extension demo directions

Author: ShMcK

SETUP.md

@@ -49,6 +49,15 @@ Some test frameworks can be modified to use tap, see a list of TAP reporters: ht
 }
 ```
 
+## Install Extension Demo
+
+1. Copy the `CodeRoad.vsix` file locally
+2. Select the extensions logo from the left hand panel
+3. In the top right of the panel, select the three dots “more” dropdown.
+   1. Choose “Install from VSIX…”
+   2. Select the `CodeRoad.vsix` file and press “Install”
+4. Open up a new folder directory in VSCode and run the extension `coderoad:start`
+
 ## Known Issues
 
 There are no known issues at this time.