Add terminal walkthrough assets

docs/first-run.md

@@ -67,5 +67,26 @@ $ uvx --from pyro-mcp pyro demo
 $ uvx --from pyro-mcp pyro mcp serve
 ```
 
+`pyro demo` proves the one-shot create/start/exec/delete VM lifecycle works end to end.
+
+Example output:
+
+```json
+{
+  "cleanup": {
+    "deleted": true,
+    "reason": "post_exec_cleanup",
+    "vm_id": "..."
+  },
+  "command": "git --version",
+  "environment": "debian:12",
+  "execution_mode": "guest_vsock",
+  "exit_code": 0,
+  "stdout": "git version ...\n"
+}
+```
+
+When you are done evaluating and want to remove stale cached environments, run `pyro env prune`.
+
 If `pyro doctor` reports `Runtime: FAIL`, or if the `pyro run` summary does not show
 `execution_mode=guest_vsock`, stop and use [troubleshooting.md](troubleshooting.md).