Update introduction.md

The code snippet that is referred to can be found below and not above.

exercises/concept/tracks-on-tracks-on-tracks/.docs/introduction.md

@@ -2,7 +2,7 @@
 
 ## Generic Types
 
-A collection definition typically includes a place holder in angle brackets, often `T` by convention. Such a collection is referred to as a generic type. This allows the collection user to specify what type of items to store in the collection. In the above example code we are instantiating a list of strings.
+A collection definition typically includes a place holder in angle brackets, often `T` by convention. Such a collection is referred to as a generic type. This allows the collection user to specify what type of items to store in the collection. In the example code below we are instantiating a list of strings.
 
 ## Lists