Minor edit

Author: lizbur10

README.md

@@ -91,9 +91,9 @@ function exerciseRoutine(postRunActivity) {
 }
 ```
 
-Notice that, in `exerciseRoutine()`, the `postRunActivity` parameter is actually
-a _function_ — we call it after we call `runFiveMiles()`. Now let's try to use
-this new function we created in our `Monday()` function:
+Notice that, in `exerciseRoutine()`, the `postRunActivity` parameter is a
+_callback function_ — we call it after we call `runFiveMiles()`. Now let's try
+to use this new function we created in our `Monday()` function:
 
 ```js
 function Monday() {