Fix bug in knights_archers_zombies doc code

pettingzoo/butterfly/knights_archers_zombies/knights_archers_zombies.py

@@ -132,6 +132,7 @@
   vector_state=True,
   use_typemasks=False,
   sequence_space=False,
+)
 ```
 
 `spawn_rate`:  how many cycles before a new zombie is spawned. A lower number means zombies are spawned at a higher rate.