Snippet format update

To match the starter (for the migration)

snippets/uniqueElements.md

@@ -1,4 +1,7 @@
-### uniqueElements
+---
+title: uniqueElements
+tags: array,beginner
+---
 
 Returns all unique values of an array.
 
@@ -10,4 +13,4 @@ const uniqueElements = arr => [...new Set(arr)];
 
 ```js
 uniqueElements([1, 2, 2, 3, 4, 4, 5]); // [1, 2, 3, 4, 5]
-```
+```