Add where to set the API key in the json file (#107)

src/index.ts

@@ -354,7 +354,7 @@ program
 
       if (!apiKey) {
         console.error(
-          "❌ Error: API key required. Set GROK_API_KEY environment variable, use --api-key flag, or save to ~/.grok/user-settings.json"
+          "❌ Error: API key required. Set GROK_API_KEY environment variable, use --api-key flag, or set \"apiKey\" field in ~/.grok/user-settings.json"
         );
         process.exit(1);
       }