Snippet format update

To match the starter (for the migration)

snippets/countBy.md

@@ -1,4 +1,7 @@
-### countBy
+---
+title: countBy
+tags: array,object,intermediate
+---
 
 Groups the elements of an array based on the given function and returns the count of elements in each group.
 
@@ -16,4 +19,4 @@ const countBy = (arr, fn) =>
 ```js
 countBy([6.1, 4.2, 6.3], Math.floor); // {4: 1, 6: 2}
 countBy(['one', 'two', 'three'], 'length'); // {3: 2, 5: 1}
-```
+```