Add postCreateCommand

.devcontainer/devcontainer.json

@@ -30,6 +30,9 @@
 
 	// Use 'postCreateCommand' to run commands after the container is created.
 	 "postCreateCommand": "npm ci && npm run build",
+		 
+	// Use 'postCreateCommand' to install the Open Reusables extension.
+	 "postCreateCommand": "code --install-extension .vscode/open-reusable-1.3.0.vsix",
 
 	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
 	"remoteUser": "node"