Snippet format update

To match the starter (for the migration)

snippets/differenceWith.md

@@ -1,4 +1,7 @@
-### differenceWith
+---
+title: differenceWith
+tags: array,function,intermediate
+---
 
 Filters out all values from an array for which the comparator function does not return `true`.
 
@@ -10,4 +13,4 @@ const differenceWith = (arr, val, comp) => arr.filter(a => val.findIndex(b => co
 
 ```js
 differenceWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0], (a, b) => Math.round(a) === Math.round(b)); // [1, 1.2]
-```
+```