Added change log for the Data Formats part of the guide

docs/en_us/data/source/index.rst

@@ -36,11 +36,12 @@ Specific Problem Types
 
 Internal Data Formats
 ---------------------
-These document describe how we store course structure, student state/progress, and events internally. Useful for developers or researchers who interact with our raw data exports.
+These documents describe how we store course structure, student state/progress, and events internally. Useful for developers or researchers who interact with our raw data exports.
 
 .. toctree::
    :maxdepth: 2
 
+   internal_data_formats/change_log.rst
    internal_data_formats/sql_schema.rst
    internal_data_formats/discussion_data.rst
    internal_data_formats/wiki_data.rst

docs/en_us/data/source/internal_data_formats/change_log.rst

+
+**********
+Change Log
+**********
+
+
+.. list-table::
+   :widths: 15 75
+   :header-rows: 1
+
+   * - Date
+     - Change
+   * - 14 Feb 14
+     - Added the ``seek_video`` and ``speed_change_video`` event types to the :ref:`Tracking Logs` chapter.
+