Snippet format update

To match the starter (for the migration)

snippets/average.md

@@ -1,4 +1,7 @@
-### average
+---
+title: average
+tags: math,array,beginner
+---
 
 Returns the average of two or more numbers.
 
@@ -11,4 +14,4 @@ const average = (...nums) => nums.reduce((acc, val) => acc + val, 0) / nums.leng
 ```js
 average(...[1, 2, 3]); // 2
 average(1, 2, 3); // 2
-```
+```