Added DOI column in the "more information" example

In the "If we want more information" example, added a new column to the SQL code so that the student would see additional information.

Author: RonHLEb

episodes/02-selecting-sorting-data.md

@@ -53,7 +53,7 @@ FROM articles;
 If we want more information, we can add a new column to the list of fields right after `SELECT`:
 
 ~~~
-SELECT Title, Authors, ISSNs, Year
+SELECT Title, Authors, ISSNs, Year, DOI
 FROM articles;
 ~~~
 {: .sql}