fixed typo in citibike nb (#137)

Co-authored-by: ysqyang <v-yangqi@microsoft.com>

notebooks/container_inventory_management/rl_formulation.ipynb

@@ -6,7 +6,7 @@
    "source": [
     "# Quick Start\n",
     "\n",
-    "This notebook demonstrates how to use MARO's reinforcement learning (RL) toolkit to solve the container inventory management ([CIM](https://maro.readthedocs.io/en/latest/scenarios/container_inventory_management.html)) problem. It is formalized as a multi-agent reinforment learning problem, where each port acts as a decision agent. The agents take actions independently, e.g., loading containers to vessels or discharging containers from vessels.   "
+    "This notebook demonstrates how to use MARO's reinforcement learning (RL) toolkit to solve the container inventory management ([CIM](https://maro.readthedocs.io/en/latest/scenarios/container_inventory_management.html)) problem. It is formalized as a multi-agent reinforcement learning problem, where each port acts as a decision agent. The agents take actions independently, e.g., loading containers to vessels or discharging containers from vessels.   "
    ]
   },
   {