md cleanup

Author: MonkeyIsNull

data_types.md

@@ -2,6 +2,7 @@
 * Spend some time in iex looking at the functions for
   Map, List, Keyword. For example, type in Map and then ```.```
   and then hit tab. Read the doc for some eg: ```h List.delete```
+
 ## List Exercises
 * Create a list with six star wars characters
 * Get the third item out of the list