Fix exercise 6.1 description, it's confusing

gamma is discount rate, not learning rate
these are different things
learning rate is alpha, there is no learning rate in Policy Evaluation

labs/notebooks/reinforcement_learning/exercises_1_4.ipynb

@@ -33,7 +33,7 @@
     "for i in range(20):\n",
     "    print(state_value_function)\n",
     "    \n",
-    "    state_value_function=#TODO: Implement the Policy Evaluation Update with a Learning Rate of 0.1\n",
+    "    state_value_function=#TODO: Implement the Policy Evaluation Update with a Discount Rate of 0.1\n",
     "print(state_value_function)"
    ]
   },
@@ -54,7 +54,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "solution=#TODO: Implement the linear programming solution with a learning rate of 0.1\n",
+    "solution=#TODO: Implement the linear programming solution with a discount rate of 0.1\n",
     "print(solution)"
    ]
   },