Typo fix

Author: Yuval Fernbach

1_Monitoring_your_TensorFlow_scripts.ipynb

@@ -223,7 +223,7 @@
     "\n",
     "Add tb_callback to the model.fit callbacks list.\n",
     "```python\n",
-    "callbacks=[previous_value,tb_callback]\n",
+    "callbacks=[checkpoint, tb_callback]\n",
     "```"
    ]
   },
@@ -275,13 +275,14 @@
    "metadata": {},
    "source": [
     "### Install Tensorboard on your local machine\n",
-    "Install [TensorBoard](https://github.com/tensorflow/tensorboard) locally using `pip install tensorboard`.  \n",
-    "To access an S3 log directory, configure the TensorBoard default region. You can do this by configuring an environment variable named AWS_REGION, and setting the value of the environment variable to the AWS region your training jobs run in.  \n",
+    "Install [TensorBoard](https://github.com/tensorflow/tensorboard) locally (On you computer) using `pip install tensorboard`.  \n",
+    "To access an S3 log directory, configure the TensorBoard default region.  \n",
+    "You can do this by configuring an environment variable named AWS_REGION, and setting the value of the environment variable to the AWS region your training job runs in.  \n",
     "For example, `AWS_REGION='us-east-1' tensorboard --logdir model_dir`  \n",
     "\n",
     "**You can get your TensorBoard command from the next cell.**\n",
     "\n",
-    "You'll need and AccessKey + SecretKey with access to model_dir for this Event, get those from https://dashboard.eventengine.run/dashboard.  \n",
+    "You'll need an AccessKey + SecretKey with access to model_dir for this Event, get those from https://dashboard.eventengine.run/dashboard.  \n",
     "\n",
     "AWS Console -> copy the Credentials / CLI Snippets and run in your Terminal / CMD."
    ]