Snippet format update

To match the starter (for the migration)

snippets/findLastIndex.md

@@ -1,4 +1,7 @@
-### findLastIndex
+---
+title: findLastIndex
+tags: array,function,intermediate
+---
 
 Returns the index of the last element for which the provided function returns a truthy value.
 
@@ -17,4 +20,4 @@ const findLastIndex = (arr, fn) =>
 ```js
 findLastIndex([1, 2, 3, 4], n => n % 2 === 1); // 2 (index of the value 3)
 findLastIndex([1, 2, 3, 4], n => n === 5); // -1 (default value when not found)
-```
+```