add additional information section

Author: Sam Kleinman

source/includes/extracts-additional-information.yaml

@@ -0,0 +1,9 @@
+ref: additional-resources-aggregation-introduction
+append: /core/aggregation-introduction.txt
+title: "Additional Resources"
+content: |
+  - `MongoDB Analytics: Learn Aggregation by Example: Exploratory Analytics and Visualization Using Flight Data <http://www.mongodb.com/presentations/mongodb-analytics-learn-aggregation-example-exploratory-analytics-and-visualization>`_
+  - `MongoDB for Time Series Data: Analyzing Time Series Data Using the Aggregation Framework and Hadoop <http://www.mongodb.com/presentations/mongodb-time-series-data-part-2-analyzing-time-series-data-using-aggregation-framework>`_
+  - `The Aggregation Framework <https://www.mongodb.com/presentations/aggregation-framework-0>`_
+style: commref
+...