Snippet format update

To match the starter (for the migration)

snippets/groupBy.md

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