updated instructions week2 enumerators

week2/codeprimer.md

@@ -97,6 +97,18 @@ var dollars : float :
 
 This simple set of formatters convert the “dollars” value to store them in memory as cents.
 
+### Enumerators
+
+Enumerators are a collection that allows you to list out valid values for a property with a descriptive name.
+
+For example, if you were making a 2D Platform game you might list out the directions your player character can be facing, like this:
+
+```enum FaceDirection{LEFT, RIGHT}```
+
+You could then use this enumerator to ensure a variable keeping track of your direction could no be assigned an invalid value like UP or DOWN.
+
+```var facing:FaceDirection = FaceDirection.LEFT```
+
 ### Decorators
 
 In Godot decorators can be used to control when a variable will be assigned. This is a convenience outside of placing the variable assignment in a function.