Update game_serve.py

script/game_serve.py

@@ -27,6 +27,7 @@ try:
 except ImportError:
     print("mUDP module not found.   pip install -U mudp")
     print("If launching, venv run source venv/bin/activate and then  pip install -U mudp")
+    print("use deactivate to exit venv when done")
     exit(1)
 try:
     sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))