Updated doom notebook url

ml5/2_6_1_Q-Learning.ipynb

@@ -369,7 +369,7 @@
     "# Optional exercises\n",
     "\n",
     "## Doom\n",
-    "Read this [article](https://medium.freecodecamp.org/an-introduction-to-deep-q-learning-lets-play-doom-54d02d8017d8) and execute the companion [notebook](https://github.com/simoninithomas/Deep_reinforcement_learning_Course/tree/master/DQN%20Doom). Analyze the results and provide conclusions about DQN."
+    "Read this [article](https://medium.freecodecamp.org/an-introduction-to-deep-q-learning-lets-play-doom-54d02d8017d8) and execute the companion [notebook](https://github.com/simoninithomas/Deep_reinforcement_learning_Course/blob/master/Deep%20Q%20Learning/Doom/Deep%20Q%20learning%20with%20Doom.ipynb). Analyze the results and provide conclusions about DQN."
    ]
   },
   {