Apply suggestions from code review

Author: Svetlana Karslioglu

beginner_source/text_sentiment_ngrams_tutorial.py

@@ -11,11 +11,13 @@
 
 Prerequisites
 ~~~~~~~~~~~~~~~~
-   - A recent 2.x version of the ``portalocker`` package needs to be installed prior to running the tutorial.
-     For example, in the Colab environment, this can be done by adding the following line at the top of the script:
-     .. code-block:: bash 
+
+- A recent 2.x version of the ``portalocker`` package needs to be installed prior to running the tutorial.
+For example, in the Colab environment, this can be done by adding the following line at the top of the script:
+
+.. code-block:: bash 
      
-        !pip install -U portalocker>=2.0.0`
+    !pip install -U portalocker>=2.0.0`
 
 """